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/agent_core/interface.py

@@ -19,9 +19,9 @@ All methods return effects that can be logged, audited, and replayed.
 import uuid
 from abc import ABC, abstractmethod
 from dataclasses import dataclass, field
-from datetime import datetime, timezone
+from datetime import UTC, datetime
 from enum import Enum, auto
-from typing import Any, Optional
+from typing import Any
 
 
 class PerceptionType(Enum):
@@ -74,7 +74,7 @@ class AgentIdentity:
     id: str
     name: str
     version: str
-    created_at: str = field(default_factory=lambda: datetime.now(timezone.utc).isoformat())
+    created_at: str = field(default_factory=lambda: datetime.now(UTC).isoformat())
 
     @classmethod
     def generate(cls, name: str, version: str = "1.0.0") -> "AgentIdentity":
@@ -96,7 +96,7 @@ class Perception:
 
     type: PerceptionType
     data: Any  # Content depends on type
-    timestamp: str = field(default_factory=lambda: datetime.now(timezone.utc).isoformat())
+    timestamp: str = field(default_factory=lambda: datetime.now(UTC).isoformat())
     source: str = "unknown"  # e.g., "camera_1", "microphone", "user_input"
     metadata: dict = field(default_factory=dict)
 
@@ -129,9 +129,9 @@ class Action:
 
     type: ActionType
     payload: Any  # Action-specific data
-    timestamp: str = field(default_factory=lambda: datetime.now(timezone.utc).isoformat())
+    timestamp: str = field(default_factory=lambda: datetime.now(UTC).isoformat())
     confidence: float = 1.0  # 0-1, agent's certainty
-    deadline: Optional[str] = None  # When action must complete
+    deadline: str | None = None  # When action must complete
 
     @classmethod
     def respond(cls, text: str, confidence: float = 1.0) -> "Action":
@@ -163,14 +163,14 @@ class Memory:
     content: Any
     created_at: str
     access_count: int = 0
-    last_accessed: Optional[str] = None
+    last_accessed: str | None = None
     importance: float = 0.5  # 0-1, for pruning decisions
     tags: list[str] = field(default_factory=list)
 
     def touch(self) -> None:
         """Mark memory as accessed."""
         self.access_count += 1
-        self.last_accessed = datetime.now(timezone.utc).isoformat()
+        self.last_accessed = datetime.now(UTC).isoformat()
 
 
 @dataclass
@@ -180,7 +180,7 @@ class Communication:
     sender: str
     recipient: str
     content: Any
-    timestamp: str = field(default_factory=lambda: datetime.now(timezone.utc).isoformat())
+    timestamp: str = field(default_factory=lambda: datetime.now(UTC).isoformat())
     protocol: str = "direct"  # e.g., "http", "websocket", "speech"
     encrypted: bool = False
 
@@ -321,10 +321,9 @@ class TimAgent(ABC):
             "state": self._state.copy(),
         }
 
-    def shutdown(self) -> None:
+    def shutdown(self) -> None:  # noqa: B027
         """Graceful shutdown. Persist state, close connections."""
         # Override in subclass for cleanup
-        pass
 
 
 class AgentEffect:
@@ -338,7 +337,7 @@ class AgentEffect:
     - Training: Learn from agent experiences
     """
 
-    def __init__(self, log_path: Optional[str] = None) -> None:
+    def __init__(self, log_path: str | None = None) -> None:
         self._effects: list[dict] = []
         self._log_path = log_path
 
@@ -350,7 +349,7 @@ class AgentEffect:
                 "perception_type": perception.type.name,
                 "source": perception.source,
                 "memory_id": memory_id,
-                "timestamp": datetime.now(timezone.utc).isoformat(),
+                "timestamp": datetime.now(UTC).isoformat(),
             }
         )
 
@@ -361,7 +360,7 @@ class AgentEffect:
                 "type": "reason",
                 "query": query,
                 "action_type": action_type.name,
-                "timestamp": datetime.now(timezone.utc).isoformat(),
+                "timestamp": datetime.now(UTC).isoformat(),
             }
         )
 
@@ -373,7 +372,7 @@ class AgentEffect:
                 "action_type": action.type.name,
                 "confidence": action.confidence,
                 "result_type": type(result).__name__,
-                "timestamp": datetime.now(timezone.utc).isoformat(),
+                "timestamp": datetime.now(UTC).isoformat(),
             }
         )