Feat: Implement JWT bearer token authentication

Protects image upload, delete, and tag-update endpoints behind
Bearer token auth. Public read endpoints remain open. Angular SPA
gains a login page, auth interceptor, and route guard for /upload.

- JWTAuthProvider (HS256, sub/iat/exp, secrets.compare_digest)
- POST /api/v1/auth/token login endpoint
- require_auth FastAPI dependency on all write routes
- AuthService, LoginComponent, authInterceptor, authGuard
- Detail page hides write controls for unauthenticated visitors
- 43 unit tests passing; integration tests require Docker stack

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

api/app/routers/images.py

@@ -7,9 +7,9 @@ from typing import Any
 from fastapi import APIRouter, Depends, File, Form, HTTPException, Response, UploadFile
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.auth.provider import AuthProvider
+from app.auth.provider import Identity
 from app.config import get_settings
-from app.dependencies import get_auth, get_db, get_storage
+from app.dependencies import get_db, get_storage, require_auth
 from app.models import Image
 from app.repositories.image_repo import ImageRepository
 from app.repositories.tag_repo import TagRepository
@@ -109,7 +109,7 @@ async def upload_image(
     tags: str | None = Form(None),
     db: AsyncSession = Depends(get_db),
     storage: StorageBackend = Depends(get_storage),
-    auth: AuthProvider = Depends(get_auth),
+    _: Identity = Depends(require_auth),
     settings=Depends(get_settings),
 ):
     data = await file.read()
@@ -163,7 +163,9 @@ async def upload_image(
         await storage.put(f"{hash_hex}-thumb", thumb_bytes, "image/webp")
         thumbnail_key = f"{hash_hex}-thumb"
     except Exception:
-        logger.warning("Thumbnail generation failed for %s; upload will proceed without thumbnail", hash_hex)
+        logger.warning(
+            "Thumbnail generation failed for %s; upload will proceed without thumbnail", hash_hex
+        )
 
     image = await image_repo.create(
         hash_hex=hash_hex,
@@ -285,6 +287,7 @@ async def update_image_tags(
     image_id: uuid.UUID,
     body: dict,
     db: AsyncSession = Depends(get_db),
+    _: Identity = Depends(require_auth),
 ):
     image_repo = ImageRepository(db)
     image = await image_repo.get_by_id(image_id)
@@ -314,6 +317,7 @@ async def delete_image(
     image_id: uuid.UUID,
     db: AsyncSession = Depends(get_db),
     storage: StorageBackend = Depends(get_storage),
+    _: Identity = Depends(require_auth),
 ):
     image_repo = ImageRepository(db)
     image = await image_repo.get_by_id(image_id)