fix(zed): harden OAuth lifecycle and live model support

- executors/zed.js: use exact wire values (anthropic, open_ai, google, x_ai)
  and strip incompatible Vertex safetySettings on the Google path
- shared/zedAuth.js: robust callback query parsing, reject garbage PKCS#1 v1.5
  decryptions, and thread proxyOptions when fetching LLM tokens
- oauth: preserve systemId across authorize/register/exchange lifecycle,
  renew proxy idle timeout on reuse, and ignore non-callback localhost requests
- shared/OAuthModal.js: track owned proxy in flowRef and stop at most once
- api/providers/[id]/models: add connection-scoped live Zed model resolver
- registry: unhide provider in dashboard
- tests: add unit coverage for wire format, native auth, and live models

open-sse/providers/registry/zed.js

@@ -4,7 +4,6 @@ export default {
   priority: 10,
   alias: "zd",
   uiAlias: "zd",
-  hidden: true,
   display: {
     name: "Zed",
     icon: "code",