feat: add read-only GitHub App access alongside OAuth

src/core/github-token-context.ts

@@ -0,0 +1,12 @@
+import { createHash } from "crypto";
+
+interface TokenContext { quotaKey: string; renew: (force?: boolean) => Promise<string>; }
+const contexts = new Map<string, TokenContext>();
+export function registerGitHubToken(token: string, context: TokenContext) {
+  if (contexts.size >= 2000 && !contexts.has(token)) contexts.delete(contexts.keys().next().value!);
+  contexts.set(token, context);
+}
+export function githubTokenContext(token: string) { return contexts.get(token); }
+export function githubQuotaKey(token: string) {
+  return contexts.get(token)?.quotaKey || createHash("sha256").update(token).digest("hex").slice(0, 24);
+}