feat(checklist): add daily checklist feature with admin management

Add daily checklist view for users to track daily tasks
Support creating, editing, deleting, and drag-and-drop reordering in admin panel

backend/db/schema.sql

@@ -38,6 +38,19 @@ CREATE TABLE IF NOT EXISTS user_sessions (
 CREATE INDEX IF NOT EXISTS user_sessions_user_id_idx
   ON user_sessions(user_id);
 
+CREATE TABLE IF NOT EXISTS daily_checklist_items (
+  id integer GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
+  title text NOT NULL,
+  sort_order integer NOT NULL DEFAULT 0 CHECK (sort_order >= 0),
+  created_by_user_id integer REFERENCES users(id) ON DELETE SET NULL,
+  updated_by_user_id integer REFERENCES users(id) ON DELETE SET NULL,
+  created_at timestamptz NOT NULL DEFAULT now(),
+  updated_at timestamptz NOT NULL DEFAULT now()
+);
+
+CREATE INDEX IF NOT EXISTS daily_checklist_items_sort_order_idx
+  ON daily_checklist_items(sort_order, id);
+
 CREATE TABLE IF NOT EXISTS skills (
   id integer GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
   name text NOT NULL UNIQUE,