feat: add Cloudflare AI TTS engine (aura-2-en) with voice grouping in UI

backend/cmd/runner/main.go

@@ -23,6 +23,7 @@ import (
 	"github.com/getsentry/sentry-go"
 	"github.com/libnovel/backend/internal/asynqqueue"
 	"github.com/libnovel/backend/internal/browser"
+	"github.com/libnovel/backend/internal/cfai"
 	"github.com/libnovel/backend/internal/config"
 	"github.com/libnovel/backend/internal/kokoro"
 	"github.com/libnovel/backend/internal/libretranslate"
@@ -130,6 +131,15 @@ func run() error {
 		log.Warn("POCKET_TTS_URL not set — pocket-tts voice tasks will fail")
 	}
 
+	// ── Cloudflare Workers AI ────────────────────────────────────────────────
+	var cfaiClient cfai.Client
+	if cfg.CFAI.AccountID != "" && cfg.CFAI.APIToken != "" {
+		cfaiClient = cfai.New(cfg.CFAI.AccountID, cfg.CFAI.APIToken, cfg.CFAI.Model)
+		log.Info("cloudflare AI TTS enabled", "model", cfg.CFAI.Model)
+	} else {
+		log.Info("CFAI_ACCOUNT_ID/CFAI_API_TOKEN not set — CF AI voice tasks will fail")
+	}
+
 	// ── LibreTranslate ──────────────────────────────────────────────────────
 	ltClient := libretranslate.New(cfg.LibreTranslate.URL, cfg.LibreTranslate.APIKey)
 	if ltClient != nil {
@@ -191,6 +201,7 @@ func run() error {
 		Novel:            novel,
 		Kokoro:           kokoroClient,
 		PocketTTS:        pocketTTSClient,
+		CFAI:             cfaiClient,
 		LibreTranslate:   ltClient,
 		Log:              log,
 	}