feat(notifications): add Click link to all ntfy alerts (test + real)

Test notification:
- Click header -> {PUBLIC_URL}/notifications so tapping the test opens the app

Real bill alerts (dispatcher):
- Title reformatted: "New Bill Text: HR 1234" (event type + bill identifier)
- Body: bill full name on first line, AI summary below (300 chars)
- Tags updated per event type (page, memo, siren) instead of generic scroll
- Click header was already set from bill_url; no change needed there

Authored-By: Jack Levy

backend/app/api/notifications.py

@@ -11,6 +11,7 @@ from fastapi.responses import Response
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
+from app.config import settings as app_settings
 from app.core.dependencies import get_current_user
 from app.database import get_db
 from app.models.notification import NotificationEvent
@@ -115,10 +116,12 @@ async def test_ntfy(
     if not url:
         return NotificationTestResult(status="error", detail="Topic URL is required")
 
+    base_url = (app_settings.PUBLIC_URL or app_settings.LOCAL_URL).rstrip("/")
     headers: dict[str, str] = {
         "Title": "PocketVeto: Test Notification",
         "Priority": "default",
         "Tags": "white_check_mark",
+        "Click": f"{base_url}/notifications",
     }
     if body.ntfy_auth_method == "token" and body.ntfy_token.strip():
         headers["Authorization"] = f"Bearer {body.ntfy_token.strip()}"
@@ -132,7 +135,10 @@ async def test_ntfy(
         async with httpx.AsyncClient(timeout=10) as client:
             resp = await client.post(
                 url,
-                content="Your PocketVeto notification settings are working correctly.".encode("utf-8"),
+                content=(
+                    "Your PocketVeto notification settings are working correctly. "
+                    "Real alerts will link directly to the relevant bill page."
+                ).encode("utf-8"),
                 headers=headers,
             )
             resp.raise_for_status()