Ground new Regulars in the background and add recipe fix-up API

Creating a Regular now enqueues a ground_dinner job and returns at once
with its grounding_job_id. The job grounds the dinner's recipe_url with
GroundURL, else its name with Ground, and sets grounding_status grounded
(recipe, photo, method, minutes, difficulty) or failed with a
grounding_error reason code (migration 0009). It writes only a dinner
still pending, so a fix made meanwhile wins.

GET /api/v1/dinners/{id}/recipe-candidates returns up to 3 ranked
candidates {candidate_id, title, site_name, photo_url, minutes} without
downloading photos or running the model. POST /api/v1/dinners/{id}/ground
takes exactly one of {candidate_id}, {recipe_url} or {manual: {...}} and
sets grounded or manual.

PhotoCache takes an ImageFetcher interface and recipestest provides fakes
so other packages can test grounding with fake search, fetch and model.
main wires the Grounder with normalize_recipe over the AI settings.

Maestro task: 0cbaa5bf-8be4-4cbd-aab2-891e7f1bc2b5

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/recipes/photo.go

@@ -65,22 +65,28 @@ var photoDecoders = map[string]func([]byte) (image.Image, error){
 	"webp": func(b []byte) (image.Image, error) { return webp.Decode(bytes.NewReader(b)) },
 }
 
-// PhotoCache downloads photos through a Fetcher and stores each at every
+// ImageFetcher fetches an image; *Fetcher satisfies it.
+type ImageFetcher interface {
+	FetchImage(ctx context.Context, rawURL string) (Page, error)
+}
+
+// PhotoCache downloads photos through an ImageFetcher and stores each at every
 // PhotoSizes length as {id}-{size}.jpg under PhotoDir, with a photos row.
 // Photos are deduplicated by the SHA-256 of the downloaded bytes. A
 // PhotoCache is safe for concurrent use.
 type PhotoCache struct {
-	fetcher *Fetcher
-	store   *store.Store
+	images ImageFetcher
+	store  *store.Store
 	// dir is the absolute photo directory.
 	dir string
 }
 
-// NewPhotoCache returns a PhotoCache storing photos under dataDir, creating
-// the photo directory if it is absent.
-func NewPhotoCache(fetcher *Fetcher, st *store.Store, dataDir string) (*PhotoCache, error) {
-	if fetcher == nil {
-		return nil, errors.New("recipes: nil fetcher")
+// NewPhotoCache returns a PhotoCache downloading images with images and
+// storing photos under dataDir, creating the photo directory if it is
+// absent.
+func NewPhotoCache(images ImageFetcher, st *store.Store, dataDir string) (*PhotoCache, error) {
+	if images == nil {
+		return nil, errors.New("recipes: nil image fetcher")
 	}
 	if st == nil {
 		return nil, errors.New("recipes: nil store")
@@ -92,7 +98,7 @@ func NewPhotoCache(fetcher *Fetcher, st *store.Store, dataDir string) (*PhotoCac
 	if err := os.MkdirAll(dir, 0o750); err != nil {
 		return nil, fmt.Errorf("recipes: create photo directory: %w", err)
 	}
-	return &PhotoCache{fetcher: fetcher, store: st, dir: dir}, nil
+	return &PhotoCache{images: images, store: st, dir: dir}, nil
 }
 
 // DownloadedPhoto is an image DownloadPhoto has downloaded and decoded,
@@ -108,7 +114,7 @@ type DownloadedPhoto struct {
 // whose shorter side is under PhotoMinShortSide. It records nothing, so a
 // caller can try another image before opening a transaction.
 func (c *PhotoCache) DownloadPhoto(ctx context.Context, rawURL string) (DownloadedPhoto, error) {
-	page, err := c.fetcher.FetchImage(ctx, rawURL)
+	page, err := c.images.FetchImage(ctx, rawURL)
 	if err != nil {
 		return DownloadedPhoto{}, err
 	}