Self-hosting overhauled; Deep Research (Alpha) and proxy support added

Self-Host Fixes: Reworked SELF_HOST.md and docker-compose.yaml, updated Kubernetes deployment examples, numerous stability improvements, added proxy support, Playwright integration fixes, added SearXNG support for /search endpoint.

Core Fixes & Enhancements: Fixed crawl status race conditions, added timeout enforcement for scrapeURL engines, preserved query parameters in map results, ensured screenshots execute after actions, improved PDF scraping, integrated AbortController for timeout handling, enforced SDK request timeouts.

New Features & Additions: Proxy configuration options, Deep Research (Alpha), LLM text generator endpoint.

Docker & Containerization: Production-ready Docker image for simplified self-hosted deployments.