feat(grok-cli): add Grok CLI / Grok Build provider with OAuth device-code flow (#2502)

New OAuth provider routing through cli-chat-proxy.grok.com (OpenAI Responses
API), distinct from xai (api.x.ai) and grok-web (cookie SSO):

- Registry + GrokCliExecutor: Chat Completions -> Responses transform, CLI
  fingerprint headers, virtual effort models grok-4.5-{low,medium,high}
- OAuth device-code flow (auth.x.ai) with no-PKCE, shared xAI token refresh
- store=false multi-turn continuity via reasoning encrypted_content
- Quota tracker: on-demand window + prepaid balance on dashboard
- Connection test: 402 spending-limit = soft success (auth OK, out of credits)
- Alias/oauth/provider baselines + unit tests

open-sse/executors/index.js

@@ -13,6 +13,7 @@ import { QwenExecutor } from "./qwen.js";
 import { OpenCodeExecutor } from "./opencode.js";
 import { OpenCodeGoExecutor } from "./opencode-go.js";
 import { GrokWebExecutor } from "./grok-web.js";
+import { GrokCliExecutor } from "./grok-cli.js";
 import { PerplexityWebExecutor } from "./perplexity-web.js";
 import { OllamaLocalExecutor } from "./ollama-local.js";
 import { CommandCodeExecutor } from "./commandcode.js";
@@ -39,6 +40,9 @@ const executors = {
   opencode: new OpenCodeExecutor(),
   "opencode-go": new OpenCodeGoExecutor(),
   "grok-web": new GrokWebExecutor(),
+  "grok-cli": new GrokCliExecutor(),
+  gcli: new GrokCliExecutor(), // Alias
+  gb: new GrokCliExecutor(), // Alias (Grok Build)
   "perplexity-web": new PerplexityWebExecutor(),
   "ollama-local": new OllamaLocalExecutor(),
   commandcode: new CommandCodeExecutor(),
@@ -77,6 +81,7 @@ export { QwenExecutor } from "./qwen.js";
 export { OpenCodeExecutor } from "./opencode.js";
 export { OpenCodeGoExecutor } from "./opencode-go.js";
 export { GrokWebExecutor } from "./grok-web.js";
+export { GrokCliExecutor } from "./grok-cli.js";
 export { PerplexityWebExecutor } from "./perplexity-web.js";
 export { OllamaLocalExecutor } from "./ollama-local.js";
 export { CommandCodeExecutor } from "./commandcode.js";