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

backend/app/api/admin.py

@@ -272,9 +272,10 @@ async def api_health(current_user: User = Depends(get_current_admin)):
         asyncio.to_thread(_test_govinfo),
         asyncio.to_thread(_test_newsapi),
         asyncio.to_thread(_test_gnews),
+        asyncio.to_thread(_test_rep_lookup),
         return_exceptions=True,
     )
-    keys = ["congress_gov", "govinfo", "newsapi", "google_news"]
+    keys = ["congress_gov", "govinfo", "newsapi", "google_news", "rep_lookup"]
     return {
         k: r if isinstance(r, dict) else {"status": "error", "detail": str(r)}
         for k, r in zip(keys, results)
@@ -370,6 +371,54 @@ def _test_gnews() -> dict:
         return {"status": "error", "detail": str(exc)}
 
 
+def _test_rep_lookup() -> dict:
+    import re as _re
+    import requests as req
+    def _call():
+        # Step 1: Nominatim ZIP → lat/lng
+        r1 = req.get(
+            "https://nominatim.openstreetmap.org/search",
+            params={"postalcode": "20001", "country": "US", "format": "json", "limit": "1"},
+            headers={"User-Agent": "PocketVeto/1.0"},
+            timeout=10,
+        )
+        r1.raise_for_status()
+        places = r1.json()
+        if not places:
+            return {"status": "error", "detail": "Nominatim: no result for test ZIP 20001"}
+        lat, lng = places[0]["lat"], places[0]["lon"]
+        half = 0.5
+        # Step 2: TIGERweb identify → congressional district
+        r2 = req.get(
+            "https://tigerweb.geo.census.gov/arcgis/rest/services/TIGERweb/Legislative/MapServer/identify",
+            params={
+                "f": "json",
+                "geometry": f"{lng},{lat}",
+                "geometryType": "esriGeometryPoint",
+                "sr": "4326",
+                "layers": "all",
+                "tolerance": "2",
+                "mapExtent": f"{float(lng)-half},{float(lat)-half},{float(lng)+half},{float(lat)+half}",
+                "imageDisplay": "100,100,96",
+            },
+            timeout=15,
+        )
+        r2.raise_for_status()
+        results = r2.json().get("results", [])
+        for item in results:
+            attrs = item.get("attributes", {})
+            cd_field = next((k for k in attrs if _re.match(r"CD\d+FP$", k)), None)
+            if cd_field:
+                district = str(int(str(attrs[cd_field]))) if str(attrs[cd_field]).strip("0") else "At-large"
+                return {"status": "ok", "detail": f"Nominatim + TIGERweb reachable — district {district} found for ZIP 20001"}
+        layers = [r.get("layerName") for r in results]
+        return {"status": "error", "detail": f"Reachable but no CD field found. Layers: {layers}"}
+    try:
+        return _timed(_call)
+    except Exception as exc:
+        return {"status": "error", "detail": str(exc)}
+
+
 @router.get("/task-status/{task_id}")
 async def get_task_status(task_id: str, current_user: User = Depends(get_current_admin)):
     from app.workers.celery_app import celery_app