feat: deterministic image composer - OG + square variants, branding, baked caption (v0.17.0) (#152)

Composer slots between provider bytes and sideload: corner-marked featured,
branded 1200x630 OG + 1080x1080 square with baked clamped caption, capability
ladder (Imagick -> resize-only -> pass-through, never blocks publish).
Alt-text bug fix (caption, not model name). Vendored brand PNGs + OFL Poppins.

QA: APPROVE-WITH-P2-NOTES @ 6f76df1 (qa-reviews/prautoblogger/2026-06-11-6f76df1.md)
CEO greenlight: 2026-06-11 in chat.

Agent-Session: cto-image-composer-merge-20260611

prautoblogger.php

@@ -9,7 +9,7 @@
  * Plugin Name:       PRAutoBlogger
  * Plugin URI:        https://peptiderepo.com/prautoblogger
  * Description:       Monitors social media for trending topics, generates SEO-friendly blog posts using AI, and publishes them on a daily schedule with full cost tracking and self-improvement metrics.
- * Version:           0.16.0
+ * Version:           0.17.0
  * Requires at least: 6.0
  * Requires PHP:      7.4
  * Author:            PeptideRepo
@@ -35,7 +35,7 @@ if ( ! defined( 'ABSPATH' ) ) {
 | Defined here so every file in the plugin can reference paths, versions,
 | and limits without magic strings.
 */
-define( 'PRAUTOBLOGGER_VERSION', '0.16.0' );
+define( 'PRAUTOBLOGGER_VERSION', '0.17.0' );
 define( 'PRAUTOBLOGGER_DB_VERSION', '1.1.0' );
 define( 'PRAUTOBLOGGER_PLUGIN_FILE', __FILE__ );
 define( 'PRAUTOBLOGGER_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );