feat: ZIP → rep lookup, member page redesign, letter improvements

ZIP lookup (GET /api/members/by-zip/{zip}):
- Two-step geocoding: Nominatim (ZIP → lat/lng) then Census TIGERweb
  Legislative identify (lat/lng → congressional district via GEOID)
- Handles at-large states (AK, DE, MT, ND, SD, VT, WY)
- Added rep_lookup health check to admin External API Health panel

congress_api.py fixes:
- parse_member_from_api: normalize state full name → 2-letter code
  (Congress.gov returns "Florida", DB expects "FL")
- parse_member_from_api: read district from top-level data field,
  not current_term (district is not inside the term object)

Celery beat: schedule sync_members daily at 1 AM UTC so chamber,
district, and contact info stay current without manual triggering

Members page redesign: photo avatars, party/state/chamber chips,
phone + website links, ZIP lookup form to find your reps

Draft letter improvements: pass rep_name from ZIP lookup so letter
opens with "Dear Representative Franklin," instead of generic salutation;
add has_document filter to bills list endpoint

UX additions: HelpTip component, How It Works page, "How it works"
sidebar nav link, collections page description copy

Authored-By: Jack Levy

.env.example

@@ -47,6 +47,12 @@ GEMINI_MODEL=gemini-1.5-pro
 OLLAMA_BASE_URL=http://host.docker.internal:11434
 OLLAMA_MODEL=llama3.1
 
+# ─── Google Civic Information API ─────────────────────────────────────────────
+# Used for zip code → representative lookup in the Draft Letter panel.
+# Free tier: 25,000 req/day. Enable the API at:
+# https://console.cloud.google.com/apis/library/civicinfo.googleapis.com
+CIVIC_API_KEY=
+
 # ─── News ─────────────────────────────────────────────────────────────────────
 # Free key (100 req/day): https://newsapi.org/register
 NEWSAPI_KEY=