feat: v1.0.0 — UX polish, security hardening, code quality

UI/UX:
- Bill detail page tab UI (Analysis / Timeline / Votes / Notes)
- Topic tag pills on bill detail and listing pages — filtered to known
  topics, clickable, properly labelled via shared lib/topics.ts
- Notes panel always-open in Notes tab; sign-in prompt for guests
- Collapsible sidebar with icon-only mode and localStorage persistence
- Bills page defaults to has-text filter enabled
- Follow mode dropdown transparency fix
- Favicon (Landmark icon, blue background)

Security:
- Fernet encryption for ntfy passwords at rest (app/core/crypto.py)
- Separate ENCRYPTION_SECRET_KEY env var; falls back to JWT derivation
- ntfy_password no longer returned in GET response — replaced with
  ntfy_password_set: bool; NotificationSettingsUpdate type for writes
- JWT_SECRET_KEY fail-fast on startup if using default placeholder
- get_optional_user catches (JWTError, ValueError) only, not Exception

Bug fixes & code quality:
- Dashboard N+1 topic query replaced with single OR query
- notification_utils.py topic follower N+1 replaced with batch query
- Note query in bill detail page gated on token (enabled: !!token)
- search.py max_length=500 guard against oversized queries
- CollectionCreate.validate_name wired up with @field_validator
- LLM_RATE_LIMIT_RPM default raised from 10 to 50

Authored by: Jack Levy

frontend/app/icon.svg

@@ -0,0 +1,11 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32">
+  <rect width="32" height="32" rx="6" fill="#1e40af"/>
+  <g stroke="white" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round" fill="none">
+    <line x1="4" y1="28" x2="28" y2="28"/>
+    <line x1="8"  y1="24" x2="8"  y2="15"/>
+    <line x1="13" y1="24" x2="13" y2="15"/>
+    <line x1="19" y1="24" x2="19" y2="15"/>
+    <line x1="24" y1="24" x2="24" y2="15"/>
+    <polygon points="16,5 27,13 5,13"/>
+  </g>
+</svg>