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>
bb9e9aa91f