feat: admin image generation via Cloudflare Workers AI

- Add cfai/image.go: ImageGenClient with GenerateImage, GenerateImageFromReference, AllImageModels (9 models)
- Add handlers_image.go: GET /api/admin/image-gen/models + POST /api/admin/image-gen (JSON + multipart)
- Wire ImageGen client in main.go + server.go Dependencies
- Add admin/image-gen SvelteKit page: type toggle, model selector, prompt, reference img2img, advanced options, result panel, history, save-as-cover, download
- Add SvelteKit proxy route api/admin/image-gen forwarding to Go backend
- Add admin_nav_image_gen message key to all 5 locale files
- Add Image Gen nav link to admin layout

backend/cmd/backend/main.go

@@ -124,6 +124,15 @@ func run() error {
 		log.Info("CFAI_ACCOUNT_ID/CFAI_API_TOKEN not set — CF AI voices unavailable in backend")
 	}
 
+	// ── Cloudflare Workers AI Image Generation ────────────────────────────────
+	var imageGenClient cfai.ImageGenClient
+	if cfg.CFAI.AccountID != "" && cfg.CFAI.APIToken != "" {
+		imageGenClient = cfai.NewImageGen(cfg.CFAI.AccountID, cfg.CFAI.APIToken)
+		log.Info("cloudflare AI image generation enabled")
+	} else {
+		log.Info("CFAI_ACCOUNT_ID/CFAI_API_TOKEN not set — image generation unavailable")
+	}
+
 	// ── Meilisearch (search reads only; indexing is the runner's job) ────────
 	var searchIndex meili.Client
 	if cfg.Meilisearch.URL != "" {
@@ -174,6 +183,7 @@ func run() error {
 			Kokoro:           kokoroClient,
 			PocketTTS:        pocketTTSClient,
 			CFAI:             cfaiClient,
+			ImageGen:         imageGenClient,
 			Log:              log,
 		},
 	)