feat(v2.2): async http, stored procedures, 13 new plugins, api modernization

• Add async HTTP module (src/core/http.lua) for non-blocking plugin requests
• Replace all inline SQL with PostgreSQL stored procedures
• Add 13 new plugins: autodelete, customcaptcha, slowmode, topic, poll, reactions, qr, bookmark, growth, inline, paste, rss, schedule
• Modernize all API calls to opts-based pattern
• Expand router with 8 new event hooks (reactions, polls, boosts, etc.)
• Add migration 006 for import procedures
• Add docker-compose.matticate.yml for second bot instance
• Update docs, rockspec, and plugin counts for v2.2