refactor(open-sse): translator DRY + schema enums, bug fixes, dead code cleanup

- Bug B1-B7: media UI m.kind||m.type, serviceKinds, gemini mediaPriority, schema kind, models/info lookup by kind
- Dead code D1-D6: safeParseJSON, drop PROVIDER_ENDPOINTS, orphan fetcher, GITHUB_CONFIG derive, getProviderConfig internal, legacy kiro file
- Translator concerns: toOpenAIUsage, toOpenAIFinish (gemini/kiro/ollama + fix kiro tool finish), thinking effort maps
- Reorg helpers/ → concerns/ (logic) + formats/ (per-format) + schema/ (pure enums: roles/blocks/finishReasons/defaults)
- Wire ~280 hardcoded role/block/finish/default literals to schema enums across 20+ files
- collapseTextParts + extractTextContent dedup
- Normalize translator fn names to openaiToXRequest / xToOpenAIResponse
- Golden tests lock behavior; 0 regression (byte-for-byte providers/alias, 26=26 known fails)

Co-authored-by: Cursor <cursoragent@cursor.com>

open-sse/services/provider.js

@@ -104,8 +104,8 @@ export function detectFormat(body) {
   return "openai";
 }
 
-// Get provider config
-export function getProviderConfig(provider) {
+// Get provider config (internal — no external runtime consumer)
+function getProviderConfig(provider) {
   if (isOpenAICompatible(provider)) {
     const apiType = getOpenAICompatibleType(provider);
     return {

open-sse/services/usage.js

@@ -6,15 +6,15 @@ import { CLIENT_METADATA, getPlatformUserAgent } from "../config/appConstants.js
 import { proxyAwareFetch } from "../utils/proxyFetch.js";
 import { resolveDefaultProfileArn } from "../config/kiroConstants.js";
 import { ANTIGRAVITY_OAUTH_CLIENT, ANTHROPIC_API_VERSION } from "../providers/shared.js";
-import { PROVIDERS } from "../providers/index.js";
+import { PROVIDERS, PROVIDER_OAUTH } from "../providers/index.js";
 
 // usage endpoints: single source from registry transport.usage
 const U = (id) => PROVIDERS[id]?.usage || {};
 
-// GitHub API config
+// GitHub API config — single source from registry oauth block
 const GITHUB_CONFIG = {
-  apiVersion: "2022-11-28",
-  userAgent: "GitHubCopilotChat/0.26.7",
+  apiVersion: PROVIDER_OAUTH.github?.apiVersion,
+  userAgent: PROVIDER_OAUTH.github?.userAgent,
 };
 
 // GLM quota endpoints (region-aware) — url from registry transport.usage