feat: Move all configuration tools to MCP to free context

Distract less the LLM models and reduce token usage

fix: Orphan sessions, channel conversations

fix: Render makdown tables

fix: New chat button and allow changing people types

fix: Improve calendar tooling description

fix: Tooling context, description and optimizations for LLMs

refactor: Next pages routing

feat: Unified Push support

test: security improvements

feat: security revision

Rate-limiting 5 req/min per IP to auth (login, refresh) endpoints
workingDir in executeShellCommand tool is now shell-escaped
SSRF protection for toolOpenURL and fetchThunderbirdAutoconfig
Cookie secure flag
SSH host key verification
Config file permissions not world-readable
WebSocket origin validation from CORS_ALLOWED_ORIGINS
JWT algorithm check
CORS tightening
Session limits per user