fix: use text type for channel_id to match tablos.id column type

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

supabase/migrations/20260411_create_chat_tables.sql

@@ -3,7 +3,7 @@
 -- Messages table
 CREATE TABLE IF NOT EXISTS messages (
   id            uuid PRIMARY KEY DEFAULT gen_random_uuid(),
-  channel_id    uuid NOT NULL REFERENCES tablos(id) ON DELETE CASCADE,
+  channel_id    text NOT NULL REFERENCES tablos(id) ON DELETE CASCADE,
   user_id       uuid NOT NULL REFERENCES auth.users(id),
   text          text NOT NULL,
   created_at    timestamptz NOT NULL DEFAULT now(),
@@ -16,7 +16,7 @@ CREATE INDEX IF NOT EXISTS idx_messages_channel_created ON messages(channel_id,
 -- Read state table
 CREATE TABLE IF NOT EXISTS channel_read_state (
   user_id       uuid NOT NULL REFERENCES auth.users(id),
-  channel_id    uuid NOT NULL REFERENCES tablos(id) ON DELETE CASCADE,
+  channel_id    text NOT NULL REFERENCES tablos(id) ON DELETE CASCADE,
   last_read_at  timestamptz NOT NULL DEFAULT now(),
   PRIMARY KEY (user_id, channel_id)
 );