fix: chat — VARCHAR(10) overflow for notifications type, skeleton loading

- Migration 072: widen type column to VARCHAR(20), add partial unique index for general rooms
- Backend: replace brittle ON CONFLICT with explicit SELECT-then-INSERT ensureRoom helper
- Frontend: show room skeletons (Общий чат + Уведомления) during load instead of spinner,
  hide '0 чатов' subtitle when list is empty

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

backend/migrations/072_chat_room_type_length.sql

@@ -0,0 +1,6 @@
+-- Increase type column length to fit 'notifications'
+ALTER TABLE chat_rooms ALTER COLUMN type TYPE VARCHAR(20);
+
+-- Partial unique index for general room per hotel (needed for ON CONFLICT)
+CREATE UNIQUE INDEX IF NOT EXISTS uniq_chat_rooms_general_hotel
+  ON chat_rooms(hotel_id) WHERE type = 'general';

backend/src/routes/chat.ts

@@ -13,39 +13,29 @@ const chatRoutes: FastifyPluginAsync = async (fastify) => {
   const canAccess = (userSlug: string | null, role: string, slug: string) =>
     role === 'super_admin' || userSlug === slug
 
-  // Ensure general room exists for hotel
-  const ensureGeneralRoom = async (hotelId: string) => {
+  // Ensure a room of given type exists for hotel (idempotent)
+  const ensureRoom = async (hotelId: string, type: string, name: string) => {
+    const { rows: existing } = await db.query(
+      `SELECT id FROM chat_rooms WHERE hotel_id = $1 AND type = $2 LIMIT 1`,
+      [hotelId, type],
+    )
+    if (existing[0]) return existing[0].id as string
     const { rows } = await db.query(
-      `INSERT INTO chat_rooms (hotel_id, type, name)
-       VALUES ($1, 'general', 'Общий чат')
-       ON CONFLICT (hotel_id) WHERE type = 'general' DO NOTHING
-       RETURNING id`,
-      [hotelId],
+      `INSERT INTO chat_rooms (hotel_id, type, name) VALUES ($1, $2, $3)
+       ON CONFLICT DO NOTHING RETURNING id`,
+      [hotelId, type, name],
     )
     if (rows[0]) return rows[0].id as string
-    const { rows: existing } = await db.query(
-      `SELECT id FROM chat_rooms WHERE hotel_id = $1 AND type = 'general'`,
-      [hotelId],
+    // Concurrent insert — fetch again
+    const { rows: r2 } = await db.query(
+      `SELECT id FROM chat_rooms WHERE hotel_id = $1 AND type = $2 LIMIT 1`,
+      [hotelId, type],
     )
-    return existing[0]?.id as string
+    return r2[0]?.id as string
   }
 
-  // Ensure notifications room exists for hotel
-  const ensureNotificationsRoom = async (hotelId: string) => {
-    const { rows } = await db.query(
-      `INSERT INTO chat_rooms (hotel_id, type, name)
-       VALUES ($1, 'notifications', 'Уведомления')
-       ON CONFLICT DO NOTHING
-       RETURNING id`,
-      [hotelId],
-    )
-    if (rows[0]) return rows[0].id as string
-    const { rows: existing } = await db.query(
-      `SELECT id FROM chat_rooms WHERE hotel_id = $1 AND type = 'notifications'`,
-      [hotelId],
-    )
-    return existing[0]?.id as string
-  }
+  const ensureGeneralRoom = (hotelId: string) => ensureRoom(hotelId, 'general', 'Общий чат')
+  const ensureNotificationsRoom = (hotelId: string) => ensureRoom(hotelId, 'notifications', 'Уведомления')
 
   // GET /api/hotels/:slug/chat/rooms  — list rooms (general + notifications + directs for current user)
   fastify.get<SlugParam>(