v2.3.9: Multi-part TLD Resolution, Runtime Zone Auto-Discovery & REST Purge Parity

What's Changed in AstroPress v2.3.9

• Multi-part TLD & ccTLD Resolution: Added AstroPress::get_root_domain() supporting .com.np, .org.np, .co.uk, .co.in, and other multi-part extensions, ensuring Cloudflare zones match accurately.
• Core Runtime Zone Auto-Resolution: Promoted resolve_zone_id() into the core AstroPress class with automatic runtime discovery and persistence, eliminating headless Zone ID missing errors.
• Immediate Persistence on Verification: Token verification now automatically saves OPTION_CF_API_TOKEN, OPTION_CF_ZONE_ID, and direct edge purge options immediately to the database.
• Synchronous REST & MCP Invalidation: Bypasses delayed shutdown queueing during REST API requests (defined('REST_REQUEST')) to guarantee edge cache purging succeeds on LiteSpeed/cPanel hosts.
• Decoupled Astro Webhook: Ensures Astro SSR /api/revalidate is dispatched reliably regardless of direct Cloudflare Zone API state.