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/spark/memory.py

@@ -13,9 +13,8 @@ spark_memories — consolidated insights extracted from event patterns
 import sqlite3
 import uuid
 from dataclasses import dataclass
-from datetime import datetime, timezone
+from datetime import UTC, datetime
 from pathlib import Path
-from typing import Optional
 
 DB_PATH = Path("data/spark.db")
 
@@ -31,8 +30,8 @@ class SparkEvent:
 
     id: str
     event_type: str  # task_posted, bid, assignment, completion, failure
-    agent_id: Optional[str]
-    task_id: Optional[str]
+    agent_id: str | None
+    task_id: str | None
     description: str
     data: str  # JSON payload
     importance: float  # 0.0–1.0
@@ -50,7 +49,7 @@ class SparkMemory:
     confidence: float  # 0.0–1.0
     source_events: int  # How many events contributed
     created_at: str
-    expires_at: Optional[str]
+    expires_at: str | None
 
 
 def _get_conn() -> sqlite3.Connection:
@@ -129,16 +128,16 @@ def score_importance(event_type: str, data: dict) -> float:
 def record_event(
     event_type: str,
     description: str,
-    agent_id: Optional[str] = None,
-    task_id: Optional[str] = None,
+    agent_id: str | None = None,
+    task_id: str | None = None,
     data: str = "{}",
-    importance: Optional[float] = None,
+    importance: float | None = None,
 ) -> str:
     """Record a swarm event.  Returns the event id."""
     import json
 
     event_id = str(uuid.uuid4())
-    now = datetime.now(timezone.utc).isoformat()
+    now = datetime.now(UTC).isoformat()
 
     if importance is None:
         try:
@@ -162,9 +161,9 @@ def record_event(
 
 
 def get_events(
-    event_type: Optional[str] = None,
-    agent_id: Optional[str] = None,
-    task_id: Optional[str] = None,
+    event_type: str | None = None,
+    agent_id: str | None = None,
+    task_id: str | None = None,
     limit: int = 100,
     min_importance: float = 0.0,
 ) -> list[SparkEvent]:
@@ -203,7 +202,7 @@ def get_events(
     ]
 
 
-def count_events(event_type: Optional[str] = None) -> int:
+def count_events(event_type: str | None = None) -> int:
     """Count events, optionally filtered by type."""
     conn = _get_conn()
     if event_type:
@@ -226,11 +225,11 @@ def store_memory(
     content: str,
     confidence: float = 0.5,
     source_events: int = 0,
-    expires_at: Optional[str] = None,
+    expires_at: str | None = None,
 ) -> str:
     """Store a consolidated memory.  Returns the memory id."""
     mem_id = str(uuid.uuid4())
-    now = datetime.now(timezone.utc).isoformat()
+    now = datetime.now(UTC).isoformat()
     conn = _get_conn()
     conn.execute(
         """
@@ -246,8 +245,8 @@ def store_memory(
 
 
 def get_memories(
-    memory_type: Optional[str] = None,
-    subject: Optional[str] = None,
+    memory_type: str | None = None,
+    subject: str | None = None,
     min_confidence: float = 0.0,
     limit: int = 50,
 ) -> list[SparkMemory]:
@@ -283,7 +282,7 @@ def get_memories(
     ]
 
 
-def count_memories(memory_type: Optional[str] = None) -> int:
+def count_memories(memory_type: str | None = None) -> int:
     """Count memories, optionally filtered by type."""
     conn = _get_conn()
     if memory_type: