Fix search cold-cache gate, 429 handling, and datetime.now() violations

ConnectionSearch.tsx:
- Add loading guard for useSettings() — prevents cold cache from showing
  "enable connections" gate when settings haven't loaded yet
- Add 429 rate limit handling in search catch block — shows user-friendly
  message instead of silently showing "User not found"
- Import axios for isAxiosError type guard

connections.py:
- Fix 3x datetime.now() → datetime.now(timezone.utc) per hard rule
  (lines 187, 378, 565)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/routers/connections.py

@@ -184,7 +184,7 @@ async def send_connection_request(
         raise HTTPException(status_code=409, detail="A pending request already exists")
 
     # Per-receiver cap: max 5 pending requests within 10 minutes
-    ten_min_ago = datetime.now() - timedelta(minutes=10)
+    ten_min_ago = datetime.now(timezone.utc) - timedelta(minutes=10)
     pending_count = await db.scalar(
         select(func.count())
         .select_from(ConnectionRequest)
@@ -375,7 +375,7 @@ async def _respond_to_request_inner(
     db: AsyncSession,
     current_user: User,
 ) -> RespondAcceptResponse | RespondRejectResponse:
-    now = datetime.now()
+    now = datetime.now(timezone.utc)
 
     # Atomic update — only succeeds if status is still 'pending' and receiver is current user
     result = await db.execute(
@@ -562,7 +562,7 @@ async def cancel_request(
     current_user: User = Depends(get_current_user),
 ):
     """Cancel an outgoing connection request. Atomic via UPDATE...WHERE status='pending'."""
-    now = datetime.now()
+    now = datetime.now(timezone.utc)
 
     # Atomic update — only succeeds if sender is current user and status is still pending
     result = await db.execute(

frontend/src/components/connections/ConnectionSearch.tsx

@@ -14,6 +14,7 @@ import { Button } from '@/components/ui/button';
 import { Label } from '@/components/ui/label';
 import { useConnections } from '@/hooks/useConnections';
 import { useSettings } from '@/hooks/useSettings';
+import axios from 'axios';
 import { getErrorMessage } from '@/lib/api';
 
 interface ConnectionSearchProps {
@@ -24,7 +25,7 @@ interface ConnectionSearchProps {
 
 export default function ConnectionSearch({ open, onOpenChange, personId }: ConnectionSearchProps) {
   const { search, isSearching, sendRequest, isSending } = useConnections();
-  const { settings } = useSettings();
+  const { settings, isLoading: isLoadingSettings } = useSettings();
   const navigate = useNavigate();
   const [umbralName, setUmbralName] = useState('');
   const [found, setFound] = useState<boolean | null>(null);
@@ -39,9 +40,13 @@ export default function ConnectionSearch({ open, onOpenChange, personId }: Conne
     try {
       const result = await search(umbralName.trim());
       setFound(result.found);
-    } catch {
+    } catch (err) {
+      if (axios.isAxiosError(err) && err.response?.status === 429) {
+        toast.error('Too many searches — please wait a moment and try again');
+      } else {
         setFound(false);
       }
+    }
   };
 
   const handleSend = async () => {
@@ -76,7 +81,9 @@ export default function ConnectionSearch({ open, onOpenChange, personId }: Conne
           </DialogDescription>
         </DialogHeader>
         <div className="space-y-4 pt-2">
-          {!acceptConnectionsEnabled ? (
+          {isLoadingSettings ? (
+            <div className="flex justify-center py-6"><Loader2 className="h-5 w-5 animate-spin text-muted-foreground" /></div>
+          ) : !acceptConnectionsEnabled ? (
             <div className="flex flex-col items-center gap-3 py-4 text-center">
               <AlertCircle className="h-8 w-8 text-amber-400" />
               <p className="text-sm text-muted-foreground">