fix: Block shortcode rendering during page template loading

- Added $loading_page_template flag in TemplateLoader
- template-wrapper.php sets flag before loading theme header/footer
- Shortcodes::render_template() returns early if flag is set
- Prevents recursion from theme components, widgets, or other plugins

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

includes/Frontend/TemplateLoader.php

@@ -44,6 +44,42 @@ class TemplateLoader {
      */
     private static int $shortcode_context_depth = 0;
 
+    /**
+     * Flag indicating we're currently loading a FediStream page template.
+     * This completely blocks any nested FediStream shortcode rendering.
+     *
+     * @var bool
+     */
+    private static bool $loading_page_template = false;
+
+    /**
+     * Enter page template loading mode.
+     * This blocks ALL shortcode rendering during page template loading.
+     *
+     * @return void
+     */
+    public static function enter_page_template_loading(): void {
+        self::$loading_page_template = true;
+    }
+
+    /**
+     * Exit page template loading mode.
+     *
+     * @return void
+     */
+    public static function exit_page_template_loading(): void {
+        self::$loading_page_template = false;
+    }
+
+    /**
+     * Check if we're loading a page template.
+     *
+     * @return bool
+     */
+    public static function is_loading_page_template(): bool {
+        return self::$loading_page_template;
+    }
+
     /**
      * Enter shortcode rendering context.
      * Call this before rendering shortcode content to prevent recursive shortcode processing.