[Spec Kit] Implementation progress

Implements all 88 tasks for the Reaction Image Board (specs/001-reaction-image-board):

- docker-compose.yml: postgres, minio, minio-init, api, ui services with healthchecks
- api/: FastAPI app with SQLAlchemy 2.x async, Alembic migrations, S3/MinIO storage,
  full integration + unit test suite (pytest + pytest-asyncio)
- ui/: Angular 19 standalone app (Library, Upload, Detail, NotFound components)
- .env.example: all required environment variables
- .gitignore: Python, Node, Docker, IDE, .env patterns

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

api/app/storage/backend.py

@@ -0,0 +1,15 @@
+from abc import ABC, abstractmethod
+
+
+class StorageBackend(ABC):
+    @abstractmethod
+    async def put(self, key: str, data: bytes, content_type: str) -> None:
+        """Store object at key with given content type."""
+
+    @abstractmethod
+    async def get_presigned_url(self, key: str, expires_in_seconds: int = 3600) -> str:
+        """Return a pre-signed URL valid for expires_in_seconds."""
+
+    @abstractmethod
+    async def delete(self, key: str) -> None:
+        """Delete object at key."""

api/app/storage/s3_backend.py

@@ -0,0 +1,46 @@
+from contextlib import asynccontextmanager
+
+import aiobotocore.session
+
+from app.config import get_settings
+from app.storage.backend import StorageBackend
+
+
+class S3StorageBackend(StorageBackend):
+    def __init__(self) -> None:
+        self._settings = get_settings()
+        self._session = aiobotocore.session.get_session()
+
+    @asynccontextmanager
+    async def _client(self):
+        s = self._settings
+        async with self._session.create_client(
+            "s3",
+            region_name=s.s3_region,
+            endpoint_url=s.s3_endpoint_url or None,
+            aws_access_key_id=s.s3_access_key_id,
+            aws_secret_access_key=s.s3_secret_access_key,
+        ) as client:
+            yield client
+
+    async def put(self, key: str, data: bytes, content_type: str) -> None:
+        async with self._client() as client:
+            await client.put_object(
+                Bucket=self._settings.s3_bucket_name,
+                Key=key,
+                Body=data,
+                ContentType=content_type,
+            )
+
+    async def get_presigned_url(self, key: str, expires_in_seconds: int = 3600) -> str:
+        async with self._client() as client:
+            url = await client.generate_presigned_url(
+                "get_object",
+                Params={"Bucket": self._settings.s3_bucket_name, "Key": key},
+                ExpiresIn=expires_in_seconds,
+            )
+        return url
+
+    async def delete(self, key: str) -> None:
+        async with self._client() as client:
+            await client.delete_object(Bucket=self._settings.s3_bucket_name, Key=key)