ruff (#169)

* polish: streamline nav, extract inline styles, improve tablet UX

- Restructure desktop nav from 8+ flat links + overflow dropdown into
  5 grouped dropdowns (Core, Agents, Intel, System, More) matching
  the mobile menu structure to reduce decision fatigue
- Extract all inline styles from mission_control.html and base.html
  notification elements into mission-control.css with semantic classes
- Replace JS-built innerHTML with secure DOM construction in
  notification loader and chat history
- Add CONNECTING state to connection indicator (amber) instead of
  showing OFFLINE before WebSocket connects
- Add tablet breakpoint (1024px) with larger touch targets for
  Apple Pencil / stylus use and safe-area padding for iPad toolbar
- Add active-link highlighting in desktop dropdown menus
- Rename "Mission Control" page title to "System Overview" to
  disambiguate from the chat home page
- Add "Home — Timmy Time" page title to index.html

https://claude.ai/code/session_015uPUoKyYa8M2UAcyk5Gt6h

* fix(security): move auth-gate credentials to environment variables

Hardcoded username, password, and HMAC secret in auth-gate.py replaced
with os.environ lookups. Startup now refuses to run if any variable is
unset. Added AUTH_GATE_SECRET/USER/PASS to .env.example.

https://claude.ai/code/session_015uPUoKyYa8M2UAcyk5Gt6h

* refactor(tooling): migrate from black+isort+bandit to ruff

Replace three separate linting/formatting tools with a single ruff
invocation. Updates tox.ini (lint, format, pre-push, pre-commit envs),
.pre-commit-config.yaml, and CI workflow. Fixes all ruff errors
including unused imports, missing raise-from, and undefined names.
Ruff config maps existing bandit skips to equivalent S-rules.

https://claude.ai/code/session_015uPUoKyYa8M2UAcyk5Gt6h

---------

Co-authored-by: Claude <noreply@anthropic.com>

src/dashboard/middleware/csrf.py

@@ -4,11 +4,10 @@ Provides CSRF token generation, validation, and middleware integration
 to protect state-changing endpoints from cross-site request attacks.
 """
 
-import hashlib
 import hmac
 import secrets
+from collections.abc import Callable
 from functools import wraps
-from typing import Callable, Optional
 
 from starlette.middleware.base import BaseHTTPMiddleware
 from starlette.requests import Request
@@ -112,7 +111,7 @@ class CSRFMiddleware(BaseHTTPMiddleware):
     def __init__(
         self,
         app,
-        secret: Optional[str] = None,
+        secret: str | None = None,
         cookie_name: str = "csrf_token",
         header_name: str = "X-CSRF-Token",
         form_field: str = "csrf_token",
@@ -240,7 +239,7 @@ class CSRFMiddleware(BaseHTTPMiddleware):
 
         return False
 
-    async def _validate_request(self, request: Request, csrf_cookie: Optional[str]) -> bool:
+    async def _validate_request(self, request: Request, csrf_cookie: str | None) -> bool:
         """Validate the CSRF token in the request.
 
         Checks for token in: