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/vertex-partner.js

@@ -1,6 +1,20 @@
+
 export default {
   "id": "vertex-partner",
   "alias": "vertex-partner",
+  display: {
+      "name": "Vertex Partner",
+      "icon": "cloud",
+      "color": "#34A853",
+      "textIcon": "VP",
+      "website": "https://cloud.google.com/vertex-ai/generative-ai/docs/partner-models/use-partner-models",
+      "notice": {
+          "apiKeyUrl": "https://console.cloud.google.com/iam-admin/serviceaccounts"
+      }
+  },
+  category: "apikey",
+  uiAlias: "vxp",
+  aliases: ["vxp"],
   "transport": {
     "baseUrl": "https://aiplatform.googleapis.com"
   },