Use theme CSS variables for table colors (dark mode fix)

Hardcoded light-mode hex colors in table styles broke dark mode —
header backgrounds and text were unreadable. Now uses theme CSS custom
properties (--color-border-default, --color-bg-secondary,
--color-text-primary) with light-mode fallbacks.

Bump 0.7.2 → 0.7.3.

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

prautoblogger.php

@@ -8,7 +8,7 @@ declare(strict_types=1);
  * 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:           0.7.2
+ * Version:           0.7.3
  * Requires at least: 6.0
  * Requires PHP:      7.4
  * Author:            PeptideRepo
@@ -35,7 +35,7 @@ if ( ! defined( 'ABSPATH' ) ) {
 | and limits without magic strings.
 */
 
-define( 'PRAUTOBLOGGER_VERSION', '0.7.2' );
+define( 'PRAUTOBLOGGER_VERSION', '0.7.3' );
 define( 'PRAUTOBLOGGER_DB_VERSION', '1.1.0' );
 define( 'PRAUTOBLOGGER_PLUGIN_FILE', __FILE__ );
 define( 'PRAUTOBLOGGER_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );