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/handlers/embeddingProviders/openai.js

@@ -1,30 +1,22 @@
 // OpenAI-compatible embeddings adapter (most providers)
 import { bearerAuth } from "./_base.js";
+import { PROVIDER_MEDIA } from "../../providers/index.js";
 
+// media-only providers without a registry file keep URL here; rest derive from registry media.embeddingConfig.baseUrl
 const ENDPOINTS = {
-  openai: "https://api.openai.com/v1/embeddings",
-  openrouter: "https://openrouter.ai/api/v1/embeddings",
-  mistral: "https://api.mistral.ai/v1/embeddings",
   "voyage-ai": "https://api.voyageai.com/v1/embeddings",
-  fireworks: "https://api.fireworks.ai/inference/v1/embeddings",
-  together: "https://api.together.xyz/v1/embeddings",
-  nebius: "https://api.tokenfactory.nebius.com/v1/embeddings",
-  github: "https://models.github.ai/inference/embeddings",
-  nvidia: "https://integrate.api.nvidia.com/v1/embeddings",
   "jina-ai": "https://api.jina.ai/v1/embeddings",
-  "vercel-ai-gateway": "https://ai-gateway.vercel.sh/v1/embeddings",
 };
 
+const embedCfg = (id) => PROVIDER_MEDIA[id]?.embeddingConfig || {};
+const embedUrl = (id) => embedCfg(id).baseUrl || ENDPOINTS[id];
+
 export default function createOpenAIEmbeddingAdapter(providerId) {
+  const cfg = embedCfg(providerId);
   return {
-    buildUrl: () => ENDPOINTS[providerId],
+    buildUrl: () => embedUrl(providerId),
     buildHeaders: (creds) => {
-      const headers = { "Content-Type": "application/json", ...bearerAuth(creds) };
-      if (providerId === "openrouter") {
-        headers["HTTP-Referer"] = "https://endpoint-proxy.local";
-        headers["X-Title"] = "Endpoint Proxy";
-      }
-      return headers;
+      return { "Content-Type": "application/json", ...bearerAuth(creds), ...(cfg.headers || {}) };
     },
     buildBody: (model, { input, encoding_format, dimensions }) => {
       const body = { model, input };