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/cursor.js

@@ -1,6 +1,18 @@
+
 export default {
   "id": "cursor",
   "alias": "cu",
+  display: {
+      "name": "Cursor IDE",
+      "icon": "edit_note",
+      "color": "#00D4AA",
+      "website": "https://cursor.com",
+      "notice": {
+          "signupUrl": "https://cursor.com"
+      }
+  },
+  category: "oauth",
+  uiAlias: "cu",
   "transport": {
     "baseUrl": "https://api2.cursor.sh",
     "chatPath": "/aiserver.v1.ChatService/StreamUnifiedChatWithTools",
@@ -13,6 +25,20 @@ export default {
     },
     "clientVersion": "3.1.0"
   },
+  "oauth": {
+    "apiEndpoint": "https://api2.cursor.sh",
+    "chatEndpoint": "/aiserver.v1.ChatService/StreamUnifiedChatWithTools",
+    "modelsEndpoint": "/aiserver.v1.AiService/GetDefaultModelNudgeData",
+    "api3Endpoint": "https://api3.cursor.sh",
+    "agentEndpoint": "https://agent.api5.cursor.sh",
+    "agentNonPrivacyEndpoint": "https://agentn.api5.cursor.sh",
+    "clientVersion": "3.1.0",
+    "clientType": "ide",
+    "dbKeys": {
+      "accessToken": "cursorAuth/accessToken",
+      "machineId": "storage.serviceMachineId"
+    }
+  },
   "models": [
     {
       "id": "default",