[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/tests/integration/test_serving.py

@@ -0,0 +1,41 @@
+"""
+T055 — GET /api/v1/images/{id}/file → 302 with Location header
+T056 — /file for unknown ID → 404 image_not_found
+"""
+import io
+import uuid
+import pytest
+
+
+def _minimal_webp() -> bytes:
+    # Minimal VP8L WebP
+    return (
+        b"RIFF$\x00\x00\x00WEBPVP8L\x18\x00\x00\x00"
+        b"/\x00\x00\x00\x00\x18\xf0\x1f\xfe\xff\x02\xfe\x00"
+        b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+    )
+
+
+@pytest.mark.asyncio
+async def test_file_redirect_returns_302(client):
+    data = _minimal_webp()
+    upload = await client.post(
+        "/api/v1/images",
+        files={"file": ("img.webp", io.BytesIO(data), "image/webp")},
+    )
+    assert upload.status_code in (200, 201)
+    image_id = upload.json()["id"]
+
+    # Don't follow redirects
+    response = await client.get(f"/api/v1/images/{image_id}/file", follow_redirects=False)
+    assert response.status_code == 302
+    assert "Location" in response.headers
+    assert response.headers["Location"]  # must not be empty
+
+
+@pytest.mark.asyncio
+async def test_file_unknown_id_returns_404(client):
+    response = await client.get(f"/api/v1/images/{uuid.uuid4()}/file")
+    assert response.status_code == 404
+    body = response.json()
+    assert body["code"] == "image_not_found"