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/gitlab.js

@@ -1,7 +1,17 @@
+
 export default {
-  "id": "gitlab",
-  "alias": "gitlab",
+  "id": "gitlab",  display: { name: "GitLab Duo", icon: "code", color: "#FC6D26", textIcon: "GL", website: "https://gitlab.com", notice: { signupUrl: "https://gitlab.com" } },
+  category: "oauth",
   "transport": {
-    "baseUrl": "https://gitlab.com/api/v4/chat/completions"
+    "baseUrl": "https://gitlab.com/api/v4/chat/completions",
+      auth: {"combined":true,"header":"Authorization","scheme":"bearer"},
+  },
+  "oauth": {
+    "defaultBaseUrl": "https://gitlab.com",
+    "authorizeUrlPath": "/oauth/authorize",
+    "tokenUrlPath": "/oauth/token",
+    "userInfoUrlPath": "/api/v4/user",
+    "scope": "api read_user",
+    "codeChallengeMethod": "S256"
   }
 };