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/morph.js

@@ -1,17 +0,0 @@
-export default {
-  "id": "morph",
-  "alias": "morph",
-  "transport": {
-    "baseUrl": "https://api.morphllm.com/v1/chat/completions"
-  },
-  "models": [
-    {
-      "id": "morph-v3-large",
-      "name": "Morph V3 Large"
-    },
-    {
-      "id": "morph-v3-fast",
-      "name": "Morph V3 Fast"
-    }
-  ]
-};