refactor(open-sse): B1 consolidate media endpoint URLs into registry

- image/embed/tts/search base URLs derive from media.*Config.baseUrl /
  searchViaChat.endpoint (single source); handlers read PROVIDER_MEDIA.
- ~18 hardcoded endpoints moved: bfl/fal/stability/runway/hf/gemini/
  cloudflare/recraft/sdwebui/comfyui/nanobanana image, voyage embed,
  gemini/openrouter tts, chatSearch endpoints.
- Byte-identical: PROVIDERS 62 + alias 90 baselines, image buildUrl outputs.

Co-authored-by: Cursor <cursoragent@cursor.com>

open-sse/providers/registry/sdwebui.js

@@ -11,6 +11,10 @@ export default {
   },
   category: "apikey",
   "transport": null,
+  media: {
+    serviceKinds: ["image"],
+    imageConfig: { baseUrl: "http://localhost:7860/sdapi/v1/txt2img" }
+  },
   "models": [
     {
       "id": "stable-diffusion-v1-5",