v0.11.0 — OpenRouter model picker (#111)

v0.11.0 — OpenRouter model picker (AJAX refresh + cost preview + Phase-2 asset extract)

Replaces the free-text slug inputs for analysis_model, writing_model, and editor_model with a smart picker fed by a daily-refreshed OpenRouter model registry. Picker shows context size + input/output price + provider, filters by per-field capability, previews per-generation cost using existing cost-tracker history, and keeps a custom-slug fallback. Daily registry refresh fires from inside on_daily_generation() before lock acquire — no new top-level cron event.

Commit sequence (preserved for review):
- 353aa4e  feat(models): OpenRouter model picker + AJAX refresh + cost preview
- 283fa55  fix(phpcs): resolve 4 PHPCS violations in model-registry-refresh handler
- 1b1336a  style(phpcs): fix array syntax in model field + cost tracker
- 283f9f9  style(phpcs): fix tabs vs spaces in settings-page.php
- aa78591  refactor(assets): extract model-picker refresh handler to generic-handle file

Verification
- PHPCS strict (CI scope): 0 errors / 0 warnings
- PHPUnit: 206/206 (555 assertions, 2 pre-existing skips)
- All new files under 300-line cap (field renderer 163, AJAX handler 82)
- Security: AJAX nonce + manage_options cap; output escaped; input sanitized
- Phase 2 ready: zero PRAUTOBLOGGER_* coupling in registry/picker/AJAX classes; generic asset handle peptiderepo-model-picker

QA verdict: PASS (qa-reviews/prautoblogger/2026-04-23-aa78591.md)

Out of scope (untouched): cto-review.yml, prautoblogger_image_model field (Workers AI FLUX, Phase 3), Peptide Search AI / Peptide News fields (Phase 2).

Co-authored-by: Engineer PRAutoBlogger (in-session subagent) <engineer-prautoblogger@peptiderepo.users.noreply.github.com>

includes/core/class-cost-tracker.php

@@ -210,4 +210,61 @@ class PRAutoBlogger_Cost_Tracker {
 	public function get_current_run_cost(): float {
 		return $this->current_run_cost;
 	}
+
+	/**
+	 * Get average input/output token counts for given stages over a time period.
+	 *
+	 * Used by the model picker field renderer to calculate estimated costs
+	 * per generation based on historical token usage. Maps setting IDs to their
+	 * constituting stages (e.g., writing model controls outline + draft + polish).
+	 *
+	 * @param array<string> $stages Stage names ('analysis', 'outline', 'draft', 'polish', 'review').
+	 * @param int           $days   Historical window (default 30 days).
+	 *
+	 * @return array{avg_prompt_tokens: float, avg_completion_tokens: float, sample_size: int}
+	 *         Returns empty counters if no history. Never throws.
+	 */
+	public function get_avg_tokens_for_stages( array $stages, int $days = 30 ): array {
+		global $wpdb;
+
+		if ( empty( $stages ) ) {
+			return array(
+				'avg_prompt_tokens'      => 0.0,
+				'avg_completion_tokens'  => 0.0,
+				'sample_size'            => 0,
+			);
+		}
+
+		$cutoff_time   = time() - ( $days * DAY_IN_SECONDS );
+		$stage_list    = implode( ',', array_map( array( $wpdb, 'prepare' ), array_fill( 0, count( $stages ), '%s' ), $stages ) );
+		$table_name    = $wpdb->prefix . 'prautoblogger_generation_log';
+
+		// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Prepared stage list via array_map + prepare
+		$query = $wpdb->prepare(
+			"SELECT AVG(input_tokens) as avg_input,
+                    AVG(output_tokens) as avg_output,
+                    COUNT(*) as sample_count
+             FROM $table_name
+             WHERE stage IN ( $stage_list )
+             AND timestamp >= %d",
+			$cutoff_time
+		);
+
+		// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- phpcs pragma above
+		$result = $wpdb->get_row( $query, ARRAY_A );
+
+		if ( ! $result || 0 === (int) ( $result['sample_count'] ?? 0 ) ) {
+			return array(
+				'avg_prompt_tokens'      => 0.0,
+				'avg_completion_tokens'  => 0.0,
+				'sample_size'            => 0,
+			);
+		}
+
+		return array(
+			'avg_prompt_tokens'      => (float) ( $result['avg_input'] ?? 0 ),
+			'avg_completion_tokens'  => (float) ( $result['avg_output'] ?? 0 ),
+			'sample_size'            => (int) ( $result['sample_count'] ?? 0 ),
+		);
+	}
 }