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/timmy/cli.py

@@ -1,5 +1,4 @@
 import subprocess
-from typing import Optional
 
 import typer
 
@@ -40,8 +39,8 @@ def tick():
 @app.command()
 def think(
     topic: str = typer.Argument(..., help="Topic to reason about"),
-    backend: Optional[str] = _BACKEND_OPTION,
-    model_size: Optional[str] = _MODEL_SIZE_OPTION,
+    backend: str | None = _BACKEND_OPTION,
+    model_size: str | None = _MODEL_SIZE_OPTION,
 ):
     """Ask Timmy to think carefully about a topic."""
     timmy = create_timmy(backend=backend, model_size=model_size)
@@ -51,8 +50,8 @@ def think(
 @app.command()
 def chat(
     message: str = typer.Argument(..., help="Message to send"),
-    backend: Optional[str] = _BACKEND_OPTION,
-    model_size: Optional[str] = _MODEL_SIZE_OPTION,
+    backend: str | None = _BACKEND_OPTION,
+    model_size: str | None = _MODEL_SIZE_OPTION,
 ):
     """Send a message to Timmy."""
     timmy = create_timmy(backend=backend, model_size=model_size)
@@ -61,8 +60,8 @@ def chat(
 
 @app.command()
 def status(
-    backend: Optional[str] = _BACKEND_OPTION,
-    model_size: Optional[str] = _MODEL_SIZE_OPTION,
+    backend: str | None = _BACKEND_OPTION,
+    model_size: str | None = _MODEL_SIZE_OPTION,
 ):
     """Print Timmy's operational status."""
     timmy = create_timmy(backend=backend, model_size=model_size)
@@ -71,8 +70,8 @@ def status(
 
 @app.command()
 def interview(
-    backend: Optional[str] = _BACKEND_OPTION,
-    model_size: Optional[str] = _MODEL_SIZE_OPTION,
+    backend: str | None = _BACKEND_OPTION,
+    model_size: str | None = _MODEL_SIZE_OPTION,
 ):
     """Initialize Timmy and run a structured interview.