fix: webhook message insert uses wrong schema field names

When a WhatsApp message arrives, the webhook creates/updates the contact
and conversation fine (so the conversation appears in the Inbox), but
every message INSERT fails silently because the field names don't match
the messages table schema:

  Webhook wrote              Schema has
  -----------------          ----------
  user_id                    (doesn't exist)
  whatsapp_message_id        message_id
  direction: 'inbound'       sender_type ('customer' | 'agent' | 'bot')
  message_type               content_type
  media_type                 (doesn't exist)
  status: 'received'         status ('sending'|'sent'|'delivered'|'read'|'failed')
  timestamp                  created_at

The insert error was caught and logged with console.error but silently
swallowed — the conversation update succeeded (its fields were right),
so the Inbox showed the contact and last message text, but opening the
thread showed zero messages. The 24-hour session timer also read
"no customer messages ever" and immediately marked the session expired.

Fixes in src/app/api/whatsapp/webhook/route.ts:
- processMessage() — message insert now uses the correct schema columns:
    sender_type: 'customer'
    content_type: message.type
    message_id: message.id
    status: 'delivered'
    created_at: <ISO from Meta timestamp>
- handleStatusUpdate() — lookup uses message_id (not whatsapp_message_id)
  and no longer sets updated_at (column doesn't exist on messages).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/app/api/whatsapp/webhook/route.ts

@@ -184,13 +184,13 @@ async function handleStatusUpdate(status: {
   timestamp: string
   recipient_id: string
 }) {
+  // The messages table schema uses `message_id` (not whatsapp_message_id)
+  // and has no `updated_at` column. Meta's status values (sent/delivered/
+  // read/failed) already match our CHECK constraint.
   const { error } = await supabaseAdmin()
     .from('messages')
-    .update({
-      status: status.status,
-      updated_at: new Date().toISOString(),
-    })
-    .eq('whatsapp_message_id', status.id)
+    .update({ status: status.status })
+    .eq('message_id', status.id)
 
   if (error) {
     console.error('Error updating message status:', error)
@@ -227,18 +227,23 @@ async function processMessage(
   )
   if (!conversation) return
 
-  // Insert message
+  // Insert message — field names MUST match the messages table schema
+  // (see supabase/migrations/001_initial_schema.sql):
+  //   conversation_id, sender_type, content_type, content_text,
+  //   media_url, template_name, message_id, status, created_at
+  // `mediaType` is intentionally unused — the schema has no media_type
+  // column; the MIME type is only used to construct the proxy URL during
+  // parseMessageContent. Silence the unused-var warning:
+  void mediaType
   const { error: msgError } = await supabaseAdmin().from('messages').insert({
     conversation_id: conversation.id,
-    user_id: userId,
-    whatsapp_message_id: message.id,
-    direction: 'inbound',
-    message_type: message.type,
+    sender_type: 'customer',
+    content_type: message.type,
     content_text: contentText,
     media_url: mediaUrl,
-    media_type: mediaType,
-    status: 'received',
-    timestamp: new Date(parseInt(message.timestamp) * 1000).toISOString(),
+    message_id: message.id,
+    status: 'delivered',
+    created_at: new Date(parseInt(message.timestamp) * 1000).toISOString(),
   })
 
   if (msgError) {