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/infrastructure/error_capture.py

@@ -15,8 +15,7 @@ Usage:
 import hashlib
 import logging
 import traceback
-from datetime import datetime, timedelta, timezone
-from typing import Optional
+from datetime import UTC, datetime, timedelta
 
 logger = logging.getLogger(__name__)
 
@@ -45,7 +44,7 @@ def _is_duplicate(error_hash: str) -> bool:
     """Check if this error was seen recently (within dedup window)."""
     from config import settings
 
-    now = datetime.now(timezone.utc)
+    now = datetime.now(UTC)
     window = timedelta(seconds=settings.error_dedup_window_seconds)
 
     if error_hash in _dedup_cache:
@@ -95,8 +94,8 @@ def _get_git_context() -> dict:
 def capture_error(
     exc: Exception,
     source: str = "unknown",
-    context: Optional[dict] = None,
-) -> Optional[str]:
+    context: dict | None = None,
+) -> str | None:
     """Capture an error and optionally create a bug report.
 
     Args:
@@ -165,7 +164,7 @@ def capture_error(
             f"**Source:** {source}",
             f"**File:** {affected_file}:{affected_line}",
             f"**Git:** {git_ctx.get('branch', '?')} @ {git_ctx.get('commit', '?')}",
-            f"**Time:** {datetime.now(timezone.utc).isoformat()}",
+            f"**Time:** {datetime.now(UTC).isoformat()}",
             f"**Hash:** {error_hash}",
         ]