steps 6-8: wire HybridStore into orchestrator, server, and main

- Add storage/hybrid.go: HybridStore composing PocketBase + MinIO backends
- Rewrite orchestrator to accept storage.Store instead of *writer.Writer
- Replace *writer.Writer with storage.Store in server.go and ui.go
- Wire audio cache, reading progress, chapter reads/writes through store
- Add rankingCacheAdapter in main.go to bridge context-free RankingPageCacher
  interface to HybridStore's context-aware methods

scraper/internal/server/server.go

@@ -22,7 +22,7 @@ import (
 
 	"github.com/libnovel/scraper/internal/orchestrator"
 	"github.com/libnovel/scraper/internal/scraper"
-	"github.com/libnovel/scraper/internal/writer"
+	"github.com/libnovel/scraper/internal/storage"
 )
 
 // Server wraps an HTTP mux with the scraping endpoints.
@@ -31,7 +31,7 @@ type Server struct {
 	oCfg           orchestrator.Config
 	novel          scraper.NovelScraper
 	log            *slog.Logger
-	writer         *writer.Writer
+	store          storage.Store
 	mu             sync.Mutex
 	running        bool
 	rankingRunning bool
@@ -42,26 +42,23 @@ type Server struct {
 	voiceMu      sync.RWMutex
 	cachedVoices []string // populated on first request from Kokoro /v1/audio/voices
 
-	// audioMu guards audioCache and audioInFlight.
-	// audioCache maps a cache key to the Kokoro download filename returned by
-	// POST /v1/audio/speech with return_download_link=true.
+	// audioMu guards audioInFlight only.
+	// Completed audio filenames are persisted to the Store (PocketBase).
 	// audioInFlight deduplicates concurrent generation requests for the same key.
 	audioMu       sync.Mutex
-	audioCache    map[string]string        // cacheKey → kokoro download filename
 	audioInFlight map[string]chan struct{} // cacheKey → closed when done
 }
 
 // New creates a new Server.
-func New(addr string, oCfg orchestrator.Config, novel scraper.NovelScraper, log *slog.Logger, kokoroURL, kokoroVoice string) *Server {
+func New(addr string, oCfg orchestrator.Config, novel scraper.NovelScraper, log *slog.Logger, store storage.Store, kokoroURL, kokoroVoice string) *Server {
 	return &Server{
 		addr:          addr,
 		oCfg:          oCfg,
 		novel:         novel,
 		log:           log,
-		writer:        writer.New(oCfg.StaticRoot),
+		store:         store,
 		kokoroURL:     kokoroURL,
 		kokoroVoice:   kokoroVoice,
-		audioCache:    make(map[string]string),
 		audioInFlight: make(map[string]chan struct{}),
 	}
 }
@@ -174,7 +171,7 @@ func (s *Server) handleChapterText(w http.ResponseWriter, r *http.Request) {
 		http.NotFound(w, r)
 		return
 	}
-	raw, err := s.writer.ReadChapter(slug, n)
+	raw, err := s.store.ReadChapter(r.Context(), slug, n)
 	if err != nil {
 		http.NotFound(w, r)
 		return
@@ -223,15 +220,14 @@ func (s *Server) handleAudioGenerate(w http.ResponseWriter, r *http.Request) {
 
 	cacheKey := fmt.Sprintf("%s/%d/%s/%.2f", slug, n, voice, speed)
 
-	// Fast path: already generated this session.
-	s.audioMu.Lock()
-	if filename, ok := s.audioCache[cacheKey]; ok {
-		s.audioMu.Unlock()
+	// Fast path: already generated (check persistent store first).
+	if filename, ok := s.store.GetAudioCache(r.Context(), cacheKey); ok {
 		s.writeAudioResponse(w, slug, n, voice, speed, filename)
 		return
 	}
 
 	// Deduplicate concurrent generation for the same key.
+	s.audioMu.Lock()
 	if ch, ok := s.audioInFlight[cacheKey]; ok {
 		s.audioMu.Unlock()
 		select {
@@ -240,10 +236,8 @@ func (s *Server) handleAudioGenerate(w http.ResponseWriter, r *http.Request) {
 			http.Error(w, `{"error":"request cancelled"}`, http.StatusServiceUnavailable)
 			return
 		}
-		s.audioMu.Lock()
-		filename, ok := s.audioCache[cacheKey]
-		s.audioMu.Unlock()
-		if ok {
+		// Check store again after waiting.
+		if filename, ok := s.store.GetAudioCache(r.Context(), cacheKey); ok {
 			s.writeAudioResponse(w, slug, n, voice, speed, filename)
 		} else {
 			http.Error(w, `{"error":"audio generation failed"}`, http.StatusInternalServerError)
@@ -262,7 +256,7 @@ func (s *Server) handleAudioGenerate(w http.ResponseWriter, r *http.Request) {
 	}()
 
 	// Load and validate chapter text.
-	raw, err := s.writer.ReadChapter(slug, n)
+	raw, err := s.store.ReadChapter(r.Context(), slug, n)
 	if err != nil {
 		http.Error(w, `{"error":"chapter not found"}`, http.StatusNotFound)
 		return
@@ -287,9 +281,7 @@ func (s *Server) handleAudioGenerate(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	s.audioMu.Lock()
-	s.audioCache[cacheKey] = filename
-	s.audioMu.Unlock()
+	_ = s.store.SetAudioCache(r.Context(), cacheKey, filename)
 
 	s.log.Info("audio generated", "slug", slug, "chapter", n, "filename", filename)
 	s.writeAudioResponse(w, slug, n, voice, speed, filename)
@@ -378,10 +370,7 @@ func (s *Server) handleAudioProxy(w http.ResponseWriter, r *http.Request) {
 	}
 
 	cacheKey := fmt.Sprintf("%s/%d/%s/%.2f", slug, n, voice, speed)
-	s.audioMu.Lock()
-	filename, ok := s.audioCache[cacheKey]
-	s.audioMu.Unlock()
-
+	filename, ok := s.store.GetAudioCache(r.Context(), cacheKey)
 	if !ok {
 		http.Error(w, "audio not generated yet", http.StatusNotFound)
 		return
@@ -462,7 +451,7 @@ func (s *Server) runAsync(w http.ResponseWriter, cfg orchestrator.Config) {
 		ctx, cancel := context.WithTimeout(context.Background(), 24*time.Hour)
 		defer cancel()
 
-		o := orchestrator.New(cfg, s.novel, s.log)
+		o := orchestrator.New(cfg, s.novel, s.log, s.store)
 		if err := o.Run(ctx); err != nil {
 			s.log.Error("scrape job failed", "err", fmt.Sprintf("%v", err))
 		}