feat(e2e): use direct HTTP for chapter scraping, cap TTS at 200 chars

- e2e fixture: replace single contentClient with directClient (plain HTTP)
  for chapter/metadata/ranking + contentClient (Browserless) for urlClient
  only — matches production wiring and is significantly faster
- server: add max_chars field to audio request body; truncates stripped text
  to N runes before sending to Kokoro (used by e2e for quick TTS tests)
- fix: move RankingItem to scraper package to break novelfire→storage import
  cycle; storage.RankingItem is now a type alias for backward compat
- fix: update stale New() call in novelfire integration test (missing args)
- fix: replace removed blob-ranking methods in storage integration test with
  current per-item API (UpsertRankingItem/ListRankingItems/RankingLastUpdated)
- justfile: add test-e2e and e2e tasks

scraper/internal/server/server.go

@@ -348,8 +348,9 @@ func (s *Server) handleAudioGenerate(w http.ResponseWriter, r *http.Request) {
 	voice := s.kokoroVoice
 	speed := 1.0
 	var body struct {
-		Voice string  `json:"voice"`
-		Speed float64 `json:"speed"`
+		Voice    string  `json:"voice"`
+		Speed    float64 `json:"speed"`
+		MaxChars int     `json:"max_chars"`
 	}
 	if r.Body != nil {
 		_ = json.NewDecoder(r.Body).Decode(&body)
@@ -409,6 +410,9 @@ func (s *Server) handleAudioGenerate(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, `{"error":"chapter text is empty"}`, http.StatusUnprocessableEntity)
 		return
 	}
+	if body.MaxChars > 0 && len([]rune(text)) > body.MaxChars {
+		text = string([]rune(text)[:body.MaxChars])
+	}
 	if s.kokoroURL == "" {
 		http.Error(w, `{"error":"kokoro not configured"}`, http.StatusServiceUnavailable)
 		return