v2.24.2: Improved chapter detection and robustness fixes.

Fixed

• Prevent TypeError when setting some observers if document.body is not available during early script execution.
• Avoid repeated audio track processing and duplicate logs for the same video source during SPA navigation.
• Resolved race condition where auto-generated subtitles failed to load when external tools (like SponsorBlock) performed an automatic skip during video initialization.
• Improved detection of user-initiated seeking via progress bar clicks and keyboard shortcuts to prevent overriding manual subtitle selections.
• Improved chapter detection and replacement in the side panel by updating selectors to support h3 tags for chapter titles.
• Enhanced chapter translation detection by adding a fallback to the player's chapter button when the side panel is not fully loaded.
• Increased robustness of chapter initialization by attempting detection multiple times to account for asynchronous DOM rendering.