refactor(open-sse): registry consolidation + DRY media/oauth/adhoc cleanup

- Single-source registry: oauth clientId/tokenUrl, usage URLs, image/embed
  configs, search defaultModel, codex fixedPort, google token url derive.
- Remove 29 unused OmniRoute providers (registry 100→71); media intact.
- De-adhoc: codex literals → registry format/oauth flags; reasoningInject,
  image/embed openrouter headers + xai bodyFields config-driven.
- Add REGISTRY_TEMPLATE.js + expand PROVIDER_DEFAULTS/schema JSDoc.
- Baselines updated; PROVIDERS 62 + alias 90 byte-for-byte, golden snapshots.

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

open-sse/providers/registry/mimo-free.js

@@ -1,10 +1,26 @@
+
 export default {
   "id": "mimo-free",
   "alias": "mmf",
+  display: {
+      "name": "MiMo Code Free",
+      "icon": "smart_toy",
+      "color": "#FF6900",
+      "textIcon": "MF"
+  },
+  category: "free",
+  uiAlias: "mmf",
+  noAuth: true,
+  passthroughModels: true,
   "transport": {
     "baseUrl": "https://api.xiaomimimo.com/api/free-ai/openai/chat",
     "noAuth": true
   },
+  media: {
+    noAuth: true,
+    passthroughModels: true,
+    modelsFetcher: { url: "https://models.dev/api.json", type: "mimo-free" }
+  },
   "models": [
     {
       "id": "mimo-auto",