feat(phase5): list channels - todo/in_progress/done columns, CRUD

internal/db/db.go

@@ -421,6 +421,20 @@ CREATE TABLE IF NOT EXISTS documents (
 
 CREATE INDEX IF NOT EXISTS idx_documents_channel ON documents(channel_id, updated_at DESC);
 
+-- List items (task lists)
+CREATE TABLE IF NOT EXISTS list_items (
+	id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+	channel_id UUID NOT NULL REFERENCES channels(id) ON DELETE CASCADE,
+	creator_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+	title VARCHAR(511) NOT NULL,
+	status VARCHAR(16) NOT NULL DEFAULT 'todo',
+	position INT NOT NULL DEFAULT 0,
+	created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+	updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS idx_list_items_channel ON list_items(channel_id, position);
+
 -- Message full-text search
 ALTER TABLE messages ADD COLUMN IF NOT EXISTS search_vector tsvector;
 CREATE INDEX IF NOT EXISTS idx_messages_search ON messages USING GIN(search_vector);