v0.8.2: CF images via AI Gateway + scheduled-gen timezone fix

* feat(images): route Cloudflare Workers AI via AI Gateway by default

Direct probe on 2026-04-21 confirmed the Cloudflare AI Gateway
route to Workers AI (`gateway.ai.cloudflare.com/.../workers-ai/@cf/...`)
is no longer 403ing — the upstream regression noted in v0.8.0's
ARCHITECTURE.md #16 and in thread image-pipeline seq 6 has been
resolved. Routing via the gateway gives us the same benefits we
already get for OpenRouter LLM calls: response caching, cost/latency
dashboard, rate limiting.

Changes:

- `Cloudflare_Image_Support::build_endpoint_url()` now prefers the
  gateway URL derived from the existing `prautoblogger_ai_gateway_base_url`
  option. Direct API remains the fallback.
- New private helper `build_gateway_workers_ai_url()` strips the
  OpenRouter path suffix from the configured gateway URL and appends
  `/workers-ai/{model}`. Returns empty string (fallback to direct) when:
  no gateway URL configured, the new toggle is off, or the URL isn't a
  valid `https://gateway.ai.cloudflare.com/...` shape.
- New admin toggle `prautoblogger_cf_image_via_gateway` (default on) in
  the Images section. Operators can disable to force direct API without
  clearing the LLM-path gateway URL.
- ARCHITECTURE.md #16 rewritten to reflect the v0.8.2+ gateway routing.
- CHANGELOG.md v0.8.2 entry under Changed.

Tests (new `CloudflareImageSupportTest`):

- Direct URL when gateway not configured.
- Gateway URL derived correctly when configured + toggle on.
- Toggle off forces direct URL even with gateway configured.
- Malformed gateway URL falls back to direct (defensive).
- `is_nsfw_error()` only matches error code 3030 (pinned separately so
  a tolerance regression fails early).

Cost impact: near-zero. Gateway adds a few ms of latency and enables
response caching — could *reduce* cost on identical prompts within the
configurable cache TTL.

Uninstall: new option covered by existing prautoblogger_% LIKE sweep.

Implements Commit 1b (narrow AI-Gateway-migration scope) per thread
image-pipeline seq 7.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* chore(cost): seed new toggles in activator defaults; tighten URL stripper

QA review on cd45ae2 surfaced two things; one real, one hallucinated:

- **Real (fixed):** `prautoblogger_cf_image_via_gateway` and v0.8.1's
  `prautoblogger_image_nsfw_retry` weren't seeded in
  `Activator::set_default_options()`. Belt-and-braces — the `get_option()`
  fallback at the read site already defaults to '1', so no user-visible
  regression exists, but seeding the options follows the established
  pattern for every other plugin setting and makes intent legible to
  operators inspecting `wp_options` directly.
- **Hallucinated (rejected):** the reviewer claimed
  `CloudflareImageSupportTest` methods 2–5 were empty stubs. Verified
  — every test has real `$this->assert*` calls (10 total across the 5
  cases). Ignoring. Flagging the false-positive to the CTO per the
  qa-review quality-tracking protocol.

Also clarified the docblock + tightened the ternary inside
`build_gateway_workers_ai_url()` — explicit `strrpos` false-check
instead of the `?:` short-circuit, so a no-slash base (defensive edge)
falls through cleanly instead of returning a weirdly-sliced URL.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fix(schedule): interpret `prautoblogger_schedule_time` in site timezone

Per thread scheduled-gen-timezone seq 1: WordPress core calls
`date_default_timezone_set('UTC')` early in bootstrap, so the activator's
`strtotime("tomorrow HH:MM")` was resolving in UTC regardless of the
site's configured timezone. On peptiderepo.com (Asia/Singapore, UTC+8)
a `schedule_time` of `06:00` fired at 14:00 local.

Fold this into the existing v0.8.2 branch (PR #102) since both this fix
and the earlier CF-image-gateway change target the same version and
touch overlapping files (activator, settings-fields-extended).

Changes:

- `Activator::next_daily_generation_timestamp()` — new public helper
  that reads `prautoblogger_schedule_time`, constructs a
  `DateTimeImmutable('tomorrow', wp_timezone())`, applies the
  configured hour/minute, returns a Unix timestamp. Defensive fallback
  to the old UTC-interpretation behaviour on any DateTime parse error
  so a bad tz string can't brick the schedule.
- `Activator::schedule_cron()` delegates to the helper instead of
  calling `strtotime` directly.
- New `Activator::reschedule_daily_in_site_timezone_v082()` — one-shot
  migration that clears the stale UTC-scheduled event and re-queues
  using the helper. Gated by `prautoblogger_migrated_schedule_tz_v082`
  option so it runs exactly once. Logs an INFO line comparing
  before/after next_run for auditability.
- `class-prautoblogger.php::on_check_db_version()` invokes the
  migration on every admin_init; the one-shot flag handles re-run
  guarding (no DB_VERSION bump needed — the migration is independent
  of the schema version).
- Settings description for "Generation Time" now says
  "...in your site's configured timezone (Settings → General →
  Timezone). Current site timezone: <wp_timezone_string()>" instead
  of the ambiguous "server timezone" phrasing.

File-size compliance:
- Adding the timezone helpers pushed `class-activator.php` to 352
  lines. Extracted the 104-line `create_tables()` SQL to a new
  `class-schema-installer.php` (136 lines). Activator now 245 lines,
  schema file fully dedicated to dbDelta.

Tests (new):

- `ActivatorScheduleTest` — SGT 06:00 → 22:00 UTC prev day; UTC 06:00
  → 06:00 UTC (no-op case); Asia/Kathmandu UTC+5:45 → 00:15 UTC
  (fractional offset); malformed time input doesn't throw.
- `ActivatorMigrationTest` — pre-seeded UTC cron gets cleared and
  rescheduled in SGT; second pass is idempotent.

CHANGELOG v0.8.2 entry now also covers the timezone fix under Fixed +
the description wording change under Changed.

Implements thread `scheduled-gen-timezone` seq 1 spec.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: peptiderepo <peptiderepo@users.noreply.github.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/unit/Core/ActivatorScheduleTest.php

@@ -0,0 +1,91 @@
+<?php
+/**
+ * Tests for `PRAutoBlogger_Activator::next_daily_generation_timestamp()` —
+ * the v0.8.2 timezone-aware replacement for `strtotime("tomorrow HH:MM")`
+ * which evaluated in UTC regardless of the WordPress site timezone.
+ *
+ * See thread scheduled-gen-timezone/01-cto-handoff.md for the bug report.
+ *
+ * @package PRAutoBlogger\Tests\Core
+ */
+
+namespace PRAutoBlogger\Tests\Core;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+use Brain\Monkey\Functions;
+
+class ActivatorScheduleTest extends BaseTestCase {
+
+	/**
+	 * Stub `wp_timezone()` to return the given tz id, and seed
+	 * `prautoblogger_schedule_time` with the given value.
+	 */
+	private function with_site_tz_and_time( string $tz_id, string $time_str ): void {
+		$this->stub_get_option( [
+			'prautoblogger_schedule_time' => $time_str,
+		] );
+		Functions\when( 'wp_timezone' )->alias(
+			static fn() => new \DateTimeZone( $tz_id )
+		);
+	}
+
+	/**
+	 * On an Asia/Singapore site (UTC+8), `schedule_time = 06:00` must
+	 * resolve to 22:00 UTC the previous day — the prod bug from thread
+	 * scheduled-gen-timezone seq 1.
+	 */
+	public function test_schedule_cron_uses_site_timezone(): void {
+		$this->with_site_tz_and_time( 'Asia/Singapore', '06:00' );
+
+		$timestamp = \PRAutoBlogger_Activator::next_daily_generation_timestamp();
+
+		$this->assertGreaterThan( 0, $timestamp );
+		$utc = ( new \DateTimeImmutable( '@' . $timestamp ) )->setTimezone( new \DateTimeZone( 'UTC' ) );
+		$this->assertSame( '22:00', $utc->format( 'H:i' ), 'Expected 06:00 SGT == 22:00 UTC previous day' );
+
+		// And it really is "tomorrow" in Singapore — date part should not be today SGT.
+		$sgt = ( new \DateTimeImmutable( '@' . $timestamp ) )->setTimezone( new \DateTimeZone( 'Asia/Singapore' ) );
+		$tomorrow_sgt = ( new \DateTimeImmutable( 'tomorrow', new \DateTimeZone( 'Asia/Singapore' ) ) )->format( 'Y-m-d' );
+		$this->assertSame( $tomorrow_sgt, $sgt->format( 'Y-m-d' ) );
+	}
+
+	/**
+	 * UTC site, `06:00` input → 06:00 UTC. Behaviour unchanged for
+	 * the always-UTC case; regression guard.
+	 */
+	public function test_schedule_cron_handles_utc_site(): void {
+		$this->with_site_tz_and_time( 'UTC', '06:00' );
+
+		$timestamp = \PRAutoBlogger_Activator::next_daily_generation_timestamp();
+
+		$utc = ( new \DateTimeImmutable( '@' . $timestamp ) )->setTimezone( new \DateTimeZone( 'UTC' ) );
+		$this->assertSame( '06:00', $utc->format( 'H:i' ) );
+	}
+
+	/**
+	 * Nepal runs UTC+5:45. 06:00 local → 00:15 UTC. Guards against any
+	 * integer-hour-offset assumptions in the conversion logic.
+	 */
+	public function test_schedule_cron_handles_fractional_offset(): void {
+		$this->with_site_tz_and_time( 'Asia/Kathmandu', '06:00' );
+
+		$timestamp = \PRAutoBlogger_Activator::next_daily_generation_timestamp();
+
+		$utc = ( new \DateTimeImmutable( '@' . $timestamp ) )->setTimezone( new \DateTimeZone( 'UTC' ) );
+		$this->assertSame( '00:15', $utc->format( 'H:i' ) );
+	}
+
+	/**
+	 * Malformed `schedule_time` (e.g. blank string saved accidentally)
+	 * must not throw — `absint()` clamps to 0:0 and the helper returns
+	 * a valid timestamp. Regression guard against the "bricked schedule
+	 * on bad input" failure mode.
+	 */
+	public function test_schedule_cron_survives_malformed_time_input(): void {
+		$this->with_site_tz_and_time( 'UTC', '' );
+
+		$timestamp = \PRAutoBlogger_Activator::next_daily_generation_timestamp();
+
+		$this->assertGreaterThan( 0, $timestamp );
+	}
+}