Add Display settings: article font, font size, table borders

New "Display" admin section with three settings:
- Article Font (7 choices + theme default, Google Fonts loaded on demand)
- Article Font Size (px, 0 = theme default)
- Table Borders (toggle, on by default — adds borders, padding, striping)

Inline CSS injected via wp_head only on singular posts with
_prautoblogger_generated meta — zero impact on other pages.

Extracted Image_Model_Registry to keep settings-fields-extended under
300 lines.

Bump 0.6.3 → 0.7.0.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

includes/admin/class-image-model-registry.php

@@ -0,0 +1,83 @@
+<?php
+declare(strict_types=1);
+
+/**
+ * Static registry of available image generation models.
+ *
+ * What: Returns a hardcoded list of image models for the admin model picker.
+ *       No API discovery — updated manually when providers add/remove models.
+ * Who calls it: PRAutoBlogger_Admin_Page (model picker UI) and
+ *               PRAutoBlogger_Image_Pipeline (model validation).
+ * Dependencies: None.
+ *
+ * @see admin/class-settings-fields-extended.php — Image settings reference this registry.
+ * @see core/class-image-pipeline.php            — Validates selected model against this list.
+ */
+class PRAutoBlogger_Image_Model_Registry {
+
+	/**
+	 * Get all available image generation models.
+	 *
+	 * Each entry contains:
+	 * - id:             Model identifier used in API calls.
+	 * - name:           Human-readable display name.
+	 * - provider:       'openrouter' or 'cloudflare'.
+	 * - cost_per_image: Estimated USD cost per generation.
+	 * - capabilities:   Array of capability tags.
+	 * - description:    Short description for the admin UI.
+	 *
+	 * @return array<int, array<string, mixed>>
+	 */
+	public static function get_models(): array {
+		return [
+			[
+				'id'             => 'google/gemini-2.5-flash-image',
+				'name'           => 'Gemini 2.5 Flash Image (Nano Banana)',
+				'provider'       => 'openrouter',
+				'cost_per_image' => 0.005,
+				'capabilities'   => [ 'image_generation' ],
+				'description'    => __( 'Good quality, low cost. Recommended.', 'prautoblogger' ),
+			],
+			[
+				'id'             => 'google/gemini-3.1-flash-image-preview',
+				'name'           => 'Gemini 3.1 Flash Image (Nano Banana 2)',
+				'provider'       => 'openrouter',
+				'cost_per_image' => 0.008,
+				'capabilities'   => [ 'image_generation' ],
+				'description'    => __( 'Latest Google. Better quality.', 'prautoblogger' ),
+			],
+			[
+				'id'             => 'google/gemini-3-pro-image-preview',
+				'name'           => 'Gemini 3 Pro Image (Nano Banana Pro)',
+				'provider'       => 'openrouter',
+				'cost_per_image' => 0.03,
+				'capabilities'   => [ 'image_generation' ],
+				'description'    => __( 'Highest quality Google. Premium.', 'prautoblogger' ),
+			],
+			[
+				'id'             => 'openai/gpt-5-image-mini',
+				'name'           => 'GPT-5 Image Mini',
+				'provider'       => 'openrouter',
+				'cost_per_image' => 0.02,
+				'capabilities'   => [ 'image_generation' ],
+				'description'    => __( 'OpenAI budget image model.', 'prautoblogger' ),
+			],
+			[
+				'id'             => 'openai/gpt-5-image',
+				'name'           => 'GPT-5 Image',
+				'provider'       => 'openrouter',
+				'cost_per_image' => 0.08,
+				'capabilities'   => [ 'image_generation' ],
+				'description'    => __( 'OpenAI premium. Photorealistic.', 'prautoblogger' ),
+			],
+			[
+				'id'             => 'flux-1-schnell',
+				'name'           => 'FLUX.1 schnell (Cloudflare)',
+				'provider'       => 'cloudflare',
+				'cost_per_image' => 0.0007,
+				'capabilities'   => [ 'image_generation' ],
+				'description'    => __( 'Cheapest. Low quality, 4-step.', 'prautoblogger' ),
+			],
+		];
+	}
+}