todo List 작성 api 추가

backend/app/db.py

@@ -143,6 +143,93 @@ def init_db() -> None:
             "ON best_picks(is_active, score_total DESC);"
         )
 
+        # ── todos 테이블 ───────────────────────────────────────────────────────
+        conn.execute(
+            """
+            CREATE TABLE IF NOT EXISTS todos (
+                id          TEXT    PRIMARY KEY
+                            DEFAULT (lower(hex(randomblob(4))) || '-' || lower(hex(randomblob(2)))),
+                title       TEXT    NOT NULL,
+                description TEXT,
+                status      TEXT    NOT NULL DEFAULT 'todo'
+                            CHECK(status IN ('todo','in_progress','done')),
+                created_at  TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now')),
+                updated_at  TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now'))
+            );
+            """
+        )
+        conn.execute(
+            "CREATE INDEX IF NOT EXISTS idx_todos_created ON todos(created_at DESC);"
+        )
+
+
+# ── todos CRUD ───────────────────────────────────────────────────────────────
+
+def _todo_row_to_dict(r) -> Dict[str, Any]:
+    return {
+        "id": r["id"],
+        "title": r["title"],
+        "description": r["description"],
+        "status": r["status"],
+        "created_at": r["created_at"],
+        "updated_at": r["updated_at"],
+    }
+
+
+def get_all_todos() -> List[Dict[str, Any]]:
+    with _conn() as conn:
+        rows = conn.execute(
+            "SELECT * FROM todos ORDER BY created_at DESC"
+        ).fetchall()
+    return [_todo_row_to_dict(r) for r in rows]
+
+
+def create_todo(title: str, description: Optional[str], status: str) -> Dict[str, Any]:
+    with _conn() as conn:
+        conn.execute(
+            "INSERT INTO todos (title, description, status) VALUES (?, ?, ?)",
+            (title, description, status),
+        )
+        row = conn.execute(
+            "SELECT * FROM todos WHERE rowid = last_insert_rowid()"
+        ).fetchone()
+    return _todo_row_to_dict(row)
+
+
+def update_todo(todo_id: str, fields: Dict[str, Any]) -> Optional[Dict[str, Any]]:
+    """fields에 있는 항목만 업데이트 (PATCH 방식), updated_at 자동 갱신"""
+    allowed = {"title", "description", "status"}
+    updates = {k: v for k, v in fields.items() if k in allowed}
+    if not updates:
+        with _conn() as conn:
+            row = conn.execute("SELECT * FROM todos WHERE id = ?", (todo_id,)).fetchone()
+        return _todo_row_to_dict(row) if row else None
+
+    set_clauses = ", ".join(f"{k} = ?" for k in updates)
+    set_clauses += ", updated_at = strftime('%Y-%m-%dT%H:%M:%fZ','now')"
+    args = list(updates.values()) + [todo_id]
+
+    with _conn() as conn:
+        conn.execute(
+            f"UPDATE todos SET {set_clauses} WHERE id = ?",
+            args,
+        )
+        row = conn.execute("SELECT * FROM todos WHERE id = ?", (todo_id,)).fetchone()
+    return _todo_row_to_dict(row) if row else None
+
+
+def delete_todo(todo_id: str) -> bool:
+    with _conn() as conn:
+        cur = conn.execute("DELETE FROM todos WHERE id = ?", (todo_id,))
+    return cur.rowcount > 0
+
+
+def delete_done_todos() -> int:
+    with _conn() as conn:
+        cur = conn.execute("DELETE FROM todos WHERE status = 'done'")
+    return cur.rowcount
+
+
 def upsert_draw(row: Dict[str, Any]) -> None:
     with _conn() as conn:
         conn.execute(