cf-removal: add v0.10.0 migration + tests

New class PRAutoBlogger_Migrate_Remove_Cloudflare_V0100 (own file so
class-activator.php stays under 300 lines). Runs from
PRAutoBlogger::maybe_run_db_migrations() right after the v0.9.0
migration. Idempotent via prautoblogger_migrated_remove_cloudflare_v0100
flag option (picked up by the uninstall prefix sweep).

Migrates any user on a Cloudflare image provider to Runware FLUX.1
schnell (closest equivalent, ~bash.0006/image). Detects the three
shapes a legacy user can be in: registry-derived provider ===
'cloudflare', image_provider option === 'cloudflare', or the legacy
slug 'flux-1-schnell'.

Cleans up three now-dead options: prautoblogger_cloudflare_ai_token,
prautoblogger_cloudflare_account_id, prautoblogger_cf_image_via_gateway.
Does NOT touch prautoblogger_ai_gateway_base_url — that option is
shared with the OpenRouter AI Gateway route and must stay (live-
verified test).

Tests (tests/unit/Core/ActivatorRemoveCloudflareTest.php):
- cloudflare user → runware schnell
- non-cloudflare user preserved
- runware user preserved
- legacy 'flux-1-schnell' slug triggers migration
- second run is a no-op (does not clobber admin manual changes)
- AI Gateway URL preserved across every path

ImageModelRegistryTest updated: allowed-provider set is now
['runware','openrouter']; new test_cloudflare_entries_removed_v0100
test pins the scope boundary.

includes/class-migrate-remove-cloudflare-v0100.php

@@ -0,0 +1,99 @@
+<?php
+declare(strict_types=1);
+
+/**
+ * One-shot v0.10.0 migration — remove Cloudflare Workers AI as image provider.
+ *
+ * Cloudflare Workers AI was removed as an image provider in v0.10.0.
+ * Runware FLUX.1 schnell is 65× cheaper at equivalent quality, so any user
+ * still on a `cloudflare` provider must be migrated off — otherwise the
+ * image pipeline throws "no provider for id cloudflare" at the first
+ * generation run after upgrade.
+ *
+ * Split out of class-activator.php so that file stays under the 300-line
+ * cap. The activator's maybe_run_db_migrations() delegates here.
+ *
+ * Triggered by: PRAutoBlogger::maybe_run_db_migrations() once per admin_init
+ *               until the `prautoblogger_migrated_remove_cloudflare_v0100`
+ *               flag is set.
+ * Dependencies: PRAutoBlogger_Image_Model_Registry::provider_for() for
+ *               current-model provider derivation.
+ *
+ * @see class-activator.php                 — Parallel v0.9.0 migration.
+ * @see class-prautoblogger.php             — Calls run() during admin_init.
+ * @see class-image-model-registry.php      — Provider derivation source.
+ * @see convo/prautoblogger/threads/2026-04-cloudflare-workers-ai-removal/
+ */
+class PRAutoBlogger_Migrate_Remove_Cloudflare_V0100 {
+
+	/**
+	 * Migration flag option key. Presence = already migrated.
+	 */
+	private const FLAG = 'prautoblogger_migrated_remove_cloudflare_v0100';
+
+	/**
+	 * Run the migration. Idempotent — second + later calls are no-ops.
+	 *
+	 * Side effects: may update `prautoblogger_image_model` +
+	 *               `prautoblogger_image_provider`; always deletes
+	 *               `prautoblogger_cloudflare_ai_token`,
+	 *               `prautoblogger_cloudflare_account_id`,
+	 *               `prautoblogger_cf_image_via_gateway`; sets the
+	 *               migration flag option.
+	 *
+	 * Explicitly does NOT touch `prautoblogger_ai_gateway_base_url` —
+	 * that option is shared with the OpenRouter AI Gateway route and
+	 * must stay intact.
+	 *
+	 * @return void
+	 */
+	public static function run(): void {
+		if ( get_option( self::FLAG ) ) {
+			return;
+		}
+
+		if ( self::is_user_on_cloudflare() ) {
+			// Closest equivalent — FLUX.1 schnell, Runware-hosted, ~$0.0006/image.
+			update_option( 'prautoblogger_image_model', 'runware:100@1' );
+			update_option( 'prautoblogger_image_provider', 'runware' );
+		}
+
+		// Clean up orphaned CF Workers AI credentials + the dead gateway toggle.
+		delete_option( 'prautoblogger_cloudflare_ai_token' );
+		delete_option( 'prautoblogger_cloudflare_account_id' );
+		delete_option( 'prautoblogger_cf_image_via_gateway' );
+
+		update_option( self::FLAG, '1' );
+	}
+
+	/**
+	 * Detect whether the site is currently configured to use Cloudflare
+	 * Workers AI for image generation.
+	 *
+	 * Because the v0.10.0 image-model registry no longer contains
+	 * Cloudflare entries, `provider_for()` returns '' for legacy
+	 * `flux-1-schnell` slugs. We therefore look at three signals and
+	 * treat any of them as "on Cloudflare":
+	 *   1. Current registry-derived provider === 'cloudflare'.
+	 *   2. The legacy `prautoblogger_image_provider` option is 'cloudflare'.
+	 *   3. The legacy CF-specific slug `flux-1-schnell` is still persisted
+	 *      as the image model (pre-registry-rename installs).
+	 *
+	 * @return bool
+	 */
+	private static function is_user_on_cloudflare(): bool {
+		$curr          = (string) get_option( 'prautoblogger_image_model', '' );
+		$curr_provider = PRAutoBlogger_Image_Model_Registry::provider_for( $curr );
+
+		if ( 'cloudflare' === $curr_provider ) {
+			return true;
+		}
+
+		$legacy_provider = (string) get_option( 'prautoblogger_image_provider', '' );
+		if ( 'cloudflare' === $legacy_provider ) {
+			return true;
+		}
+
+		return 'flux-1-schnell' === $curr;
+	}
+}