feat: add recent files backend APIs (#119)

domain/recent_files/service.py

@@ -0,0 +1,23 @@
+from datetime import datetime, timezone
+
+from models.database import RecentFile
+
+
+class RecentFilesService:
+    @staticmethod
+    async def record_opened_file(user_id: int, path: str) -> dict:
+        item, created = await RecentFile.get_or_create(user_id=user_id, path=path)
+        if not created:
+            await RecentFile.filter(id=item.id).update(opened_at=datetime.now(timezone.utc))
+            await item.fetch_from_db()
+        return {"id": item.id, "path": item.path, "opened_at": item.opened_at.isoformat()}
+
+    @staticmethod
+    async def list_recent_files(user_id: int, limit: int) -> list[dict]:
+        items = await RecentFile.filter(user_id=user_id).order_by("-opened_at").limit(limit)
+        return [{"id": i.id, "path": i.path, "opened_at": i.opened_at.isoformat()} for i in items]
+
+    @staticmethod
+    async def clear_recent_files(user_id: int) -> dict:
+        deleted = await RecentFile.filter(user_id=user_id).delete()
+        return {"deleted": deleted}