feat(scouts): persist connected gmail_address on oauth callback

app/api/routes/scouts.py

@@ -530,6 +530,29 @@ async def scout_gmail_oauth_callback(
     if scout is None or scout.user_id != current_user.id:
         raise HTTPException(status.HTTP_404_NOT_FOUND, "Scout not found")
     scout.oauth_token_encrypted = encrypted
+
+    # Fetch the connected Gmail address for display.
+    try:
+        from googleapiclient.discovery import build
+        from google.oauth2.credentials import Credentials
+
+        def _fetch_email() -> str | None:
+            creds = Credentials(
+                token=creds_dict["token"],
+                refresh_token=creds_dict.get("refresh_token"),
+                token_uri=creds_dict["token_uri"],
+                client_id=creds_dict["client_id"],
+                client_secret=creds_dict["client_secret"],
+                scopes=creds_dict["scopes"],
+            )
+            service = build("gmail", "v1", credentials=creds, cache_discovery=False)
+            profile = service.users().getProfile(userId="me").execute()
+            return profile.get("emailAddress")
+
+        scout.gmail_address = await asyncio.to_thread(_fetch_email)
+    except Exception:
+        logger.exception("failed to fetch gmail address for scout %s", scout_id)
+
     await db.commit()
 
     # Attempt to set up Gmail push watch so we start receiving Pub/Sub notifications.