Add web frontend with JWT auth, RBAC, SSE dashboard, and config editor

- FastAPI + htmx + Jinja2 web frontend, started with --web flag
- JWT HS256 auth (WEB_SECRET_KEY) with httpOnly cookies; access (15 min) +
  refresh (7 day) tokens; refresh rotation + JTI revocation in data/web.db
- RBAC: superadmin > admin > reader enforced per route
- Live SSE dashboard fed by tui/events broadcast queue
- Config editor: keyword groups and channel list saved to data/runtime_config.json
  and hot-reloaded in-process (scorer.reload_from_config, signal_channel_changed)
- config.py migrated to load groups/channels from runtime_config.json;
  falls back to hardcoded defaults when file absent
- tui/events.py: subscribe/unsubscribe broadcast, set_bot_context/signal_channel_changed
- utils/scorer.py: import config as _config (fixes local binding); reload_from_config()
- utils/database.py: count_by_severity, recent_for_domains, count_by_severity_for_domains
- 53 new tests (events bus, JWT lifecycle, web DB CRUD, RBAC enforcement,
  config round-trip); total 141 passing

requirements.txt

@@ -14,3 +14,11 @@ tqdm
 # Archive extraction
 py7zr
 rarfile
+
+# Web frontend (optional — only needed with --web)
+fastapi
+uvicorn[standard]
+jinja2
+python-multipart
+bcrypt
+python-jose[cryptography]