feat: Migrate to Google Merchant API and remove Composer dependencies

- Fix ISE 500 error on plugin activation:
  - Defer wc_get_logger() call in Logger class (lazy initialization)
  - Move plugin init to plugins_loaded hook with priority 20
  - Remove invalid Google_Service_ShoppingContent_Reports instantiation

- Migrate from deprecated Content API to new Merchant API:
  - Rewrite Google API class with direct REST calls
  - Implement JWT authentication using PHP OpenSSL
  - Use WordPress wp_remote_* functions for HTTP requests
  - Support Price Competitiveness reports for competitor pricing

- Remove all Composer dependencies:
  - Delete vendor/ directory (~50 packages)
  - Delete composer.json and composer.lock
  - Remove setup scripts and related documentation

- Plugin is now fully self-contained with no external dependencies

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

informatiq-smart-google-pricing.php

@@ -3,7 +3,7 @@
  * Plugin Name: informatiq-smart-google-pricing
  * Plugin URI: https://informatiq.services
  * Description: Automatically adjusts WooCommerce sale prices based on Google Merchant Center competitor data.
- * Version: 1.0.0
+ * Version: 2.0.0
  * Author: Mălin Cenușă
  * Author URI: https://malin.ro
  * Text Domain: informatiq-smart-pricing
@@ -22,7 +22,7 @@ if ( ! defined( 'ABSPATH' ) ) {
 }
 
 // Define plugin constants.
-define( 'INFORMATIQ_SP_VERSION', '1.0.0' );
+define( 'INFORMATIQ_SP_VERSION', '2.0.0' );
 define( 'INFORMATIQ_SP_PLUGIN_FILE', __FILE__ );
 define( 'INFORMATIQ_SP_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );
 define( 'INFORMATIQ_SP_PLUGIN_URL', plugin_dir_url( __FILE__ ) );
@@ -82,8 +82,11 @@ class Informatiq_Smart_Google_Pricing {
 			return;
 		}
 
-		// Load autoloader.
-		require_once INFORMATIQ_SP_PLUGIN_DIR . 'vendor/autoload.php';
+		// Check for OpenSSL extension (required for JWT signing).
+		if ( ! extension_loaded( 'openssl' ) ) {
+			add_action( 'admin_notices', array( $this, 'openssl_missing_notice' ) );
+			return;
+		}
 
 		// Load plugin classes.
 		$this->includes();
@@ -116,6 +119,17 @@ class Informatiq_Smart_Google_Pricing {
 		<?php
 	}
 
+	/**
+	 * OpenSSL missing notice.
+	 */
+	public function openssl_missing_notice() {
+		?>
+		<div class="notice notice-error">
+			<p><?php esc_html_e( 'Informatiq Smart Google Pricing requires the PHP OpenSSL extension for Google API authentication.', 'informatiq-smart-pricing' ); ?></p>
+		</div>
+		<?php
+	}
+
 	/**
 	 * Include required files.
 	 */
@@ -190,5 +204,11 @@ function informatiq_sp() {
 	return Informatiq_Smart_Google_Pricing::instance();
 }
 
-// Initialize plugin.
-informatiq_sp();
+/**
+ * Initialize plugin after all plugins are loaded.
+ * This ensures WooCommerce functions are available.
+ */
+function informatiq_sp_init() {
+	informatiq_sp();
+}
+add_action( 'plugins_loaded', 'informatiq_sp_init', 20 );