chore: migrate to v3, Doppler secrets, clean up legacy code

- Remove all pre-v3 code: scraper, ui-v2, backend v1, ios v1+v2, legacy CI workflows
- Flatten v3/ contents to repo root
- Add Doppler secrets management (project=libnovel, config=prd)
- Add justfile with doppler run wrappers for all docker compose commands
- Strip hardcoded env fallbacks from docker-compose.yml
- Add minimal README.md
- Clean up .gitignore

backend/internal/storage/minio.go

@@ -119,10 +119,10 @@ func AvatarObjectKey(userID, ext string) string {
 	return fmt.Sprintf("%s/%s.%s", userID, ext, ext)
 }
 
-// BrowseObjectKey returns the MinIO object key for a cached browse page snapshot.
-// Format: browse/{genre}/{sort}/{status}/{type}/page-{n}.json
-func BrowseObjectKey(genre, sort, status, novelType string, page int) string {
-	return fmt.Sprintf("browse/%s/%s/%s/%s/page-%d.json", genre, sort, status, novelType, page)
+// CoverObjectKey returns the MinIO object key for a book cover image.
+// Format: covers/{slug}.jpg
+func CoverObjectKey(slug string) string {
+	return fmt.Sprintf("covers/%s.jpg", slug)
 }
 
 // chapterNumberFromKey extracts the chapter number from a MinIO object key.
@@ -201,16 +201,16 @@ func (m *minioClient) listObjectKeys(ctx context.Context, bucket, prefix string)
 	return keys, nil
 }
 
-// ── Browse operations ─────────────────────────────────────────────────────────
+// ── Cover operations ──────────────────────────────────────────────────────────
 
-// putBrowse stores raw JSON bytes for a browse page snapshot.
-func (m *minioClient) putBrowse(ctx context.Context, key string, data []byte) error {
-	return m.putObject(ctx, m.bucketBrowse, key, "application/json", data)
+// putCover stores a raw cover image in the browse bucket under covers/{slug}.jpg.
+func (m *minioClient) putCover(ctx context.Context, key, contentType string, data []byte) error {
+	return m.putObject(ctx, m.bucketBrowse, key, contentType, data)
 }
 
-// getBrowse retrieves a browse page snapshot. Returns (nil, false, nil) when
-// the object does not exist.
-func (m *minioClient) getBrowse(ctx context.Context, key string) ([]byte, bool, error) {
+// getCover retrieves a cover image. Returns (nil, "", false, nil) when the
+// object does not exist.
+func (m *minioClient) getCover(ctx context.Context, key string) ([]byte, bool, error) {
 	if !m.objectExists(ctx, m.bucketBrowse, key) {
 		return nil, false, nil
 	}
@@ -220,3 +220,25 @@ func (m *minioClient) getBrowse(ctx context.Context, key string) ([]byte, bool,
 	}
 	return data, true, nil
 }
+
+// coverExists returns true when the cover image object exists.
+func (m *minioClient) coverExists(ctx context.Context, key string) bool {
+	return m.objectExists(ctx, m.bucketBrowse, key)
+}
+
+// coverContentType inspects the first bytes of data to determine if it is
+// a JPEG or PNG image. Falls back to "image/jpeg".
+func coverContentType(data []byte) string {
+	if len(data) >= 4 {
+		// PNG magic: 0x89 0x50 0x4E 0x47
+		if data[0] == 0x89 && data[1] == 0x50 && data[2] == 0x4E && data[3] == 0x47 {
+			return "image/png"
+		}
+		// WebP: starts with "RIFF" at 0..3 and "WEBP" at 8..11
+		if len(data) >= 12 && data[0] == 'R' && data[1] == 'I' && data[2] == 'F' && data[3] == 'F' &&
+			data[8] == 'W' && data[9] == 'E' && data[10] == 'B' && data[11] == 'P' {
+			return "image/webp"
+		}
+	}
+	return "image/jpeg"
+}

backend/internal/storage/store.go

@@ -50,7 +50,7 @@ var _ bookstore.RankingStore = (*Store)(nil)
 var _ bookstore.AudioStore = (*Store)(nil)
 var _ bookstore.PresignStore = (*Store)(nil)
 var _ bookstore.ProgressStore = (*Store)(nil)
-var _ bookstore.BrowseStore = (*Store)(nil)
+var _ bookstore.CoverStore = (*Store)(nil)
 var _ taskqueue.Producer = (*Store)(nil)
 var _ taskqueue.Consumer = (*Store)(nil)
 var _ taskqueue.Reader = (*Store)(nil)
@@ -69,6 +69,7 @@ func (s *Store) WriteMetadata(ctx context.Context, meta domain.BookMeta) error {
 		"total_chapters": meta.TotalChapters,
 		"source_url":     meta.SourceURL,
 		"ranking":        meta.Ranking,
+		"rating":         meta.Rating,
 	}
 	// Upsert via filter: if exists PATCH, otherwise POST.
 	existing, err := s.getBookBySlug(ctx, meta.Slug)
@@ -138,10 +139,15 @@ type pbBook struct {
 	TotalChapters int      `json:"total_chapters"`
 	SourceURL     string   `json:"source_url"`
 	Ranking       int      `json:"ranking"`
+	Rating        float64  `json:"rating"`
 	Updated       string   `json:"updated"`
 }
 
 func (b pbBook) toDomain() domain.BookMeta {
+	var metaUpdated int64
+	if t, err := time.Parse(time.RFC3339, b.Updated); err == nil {
+		metaUpdated = t.Unix()
+	}
 	return domain.BookMeta{
 		Slug:          b.Slug,
 		Title:         b.Title,
@@ -153,6 +159,8 @@ func (b pbBook) toDomain() domain.BookMeta {
 		TotalChapters: b.TotalChapters,
 		SourceURL:     b.SourceURL,
 		Ranking:       b.Ranking,
+		Rating:        b.Rating,
+		MetaUpdated:   metaUpdated,
 	}
 }
 
@@ -401,6 +409,17 @@ func (s *Store) PresignAvatarURL(ctx context.Context, userID string) (string, bo
 	return "", false, nil
 }
 
+func (s *Store) PutAvatar(ctx context.Context, userID, ext, contentType string, data []byte) (string, error) {
+	// Delete existing avatar objects for this user before writing the new one
+	// so old extensions don't linger (e.g. old .png after uploading a .jpg).
+	_ = s.mc.deleteObjects(ctx, s.mc.bucketAvatars, userID+"/")
+	key := AvatarObjectKey(userID, ext)
+	if err := s.mc.putObject(ctx, s.mc.bucketAvatars, key, contentType, data); err != nil {
+		return "", fmt.Errorf("put avatar: %w", err)
+	}
+	return key, nil
+}
+
 func (s *Store) DeleteAvatar(ctx context.Context, userID string) error {
 	return s.mc.deleteObjects(ctx, s.mc.bucketAvatars, userID+"/")
 }
@@ -770,21 +789,32 @@ func parseAudioTask(raw json.RawMessage) (domain.AudioTask, error) {
 	}, nil
 }
 
-// ── BrowseStore ────────────────────────────────────────────────────────────────
+// ── CoverStore ─────────────────────────────────────────────────────────────────
 
-func (s *Store) PutBrowsePage(ctx context.Context, genre, sort, status, novelType string, page int, data []byte) error {
-	key := BrowseObjectKey(genre, sort, status, novelType, page)
-	if err := s.mc.putBrowse(ctx, key, data); err != nil {
-		return fmt.Errorf("PutBrowsePage: %w", err)
+func (s *Store) PutCover(ctx context.Context, slug string, data []byte, contentType string) error {
+	key := CoverObjectKey(slug)
+	if contentType == "" {
+		contentType = coverContentType(data)
+	}
+	if err := s.mc.putCover(ctx, key, contentType, data); err != nil {
+		return fmt.Errorf("PutCover: %w", err)
 	}
 	return nil
 }
 
-func (s *Store) GetBrowsePage(ctx context.Context, genre, sort, status, novelType string, page int) ([]byte, bool, error) {
-	key := BrowseObjectKey(genre, sort, status, novelType, page)
-	data, ok, err := s.mc.getBrowse(ctx, key)
+func (s *Store) GetCover(ctx context.Context, slug string) ([]byte, string, bool, error) {
+	key := CoverObjectKey(slug)
+	data, ok, err := s.mc.getCover(ctx, key)
 	if err != nil {
-		return nil, false, fmt.Errorf("GetBrowsePage: %w", err)
+		return nil, "", false, fmt.Errorf("GetCover: %w", err)
 	}
-	return data, ok, nil
+	if !ok {
+		return nil, "", false, nil
+	}
+	ct := coverContentType(data)
+	return data, ct, true, nil
+}
+
+func (s *Store) CoverExists(ctx context.Context, slug string) bool {
+	return s.mc.coverExists(ctx, CoverObjectKey(slug))
 }