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/services/usage.js

@@ -11,6 +11,7 @@ export { consumeCodexRateLimitResetCredit, getCodexRateLimitResetCredits };
 import { getKiroUsage } from "./usage/kiro.js";
 import { getMiniMaxUsage } from "./usage/minimax.js";
 import { getCodeBuddyCnUsage } from "./usage/codebuddy-cn.js";
+import { getGrokCliUsage } from "./usage/grok-cli.js";
 import {
   getQwenUsage,
   getIflowUsage,
@@ -43,6 +44,7 @@ const USAGE_HANDLERS = {
   "minimax-cn": (c) => getMiniMaxUsage(c.apiKey, c.provider, c.proxyOptions),
   "vercel-ai-gateway": (c) => getVercelAiGatewayUsage(c.apiKey, c.proxyOptions),
   "codebuddy-cn": (c) => getCodeBuddyCnUsage(c.accessToken, c.apiKey, c.providerSpecificData, c.proxyOptions),
+  "grok-cli": (c) => getGrokCliUsage(c.accessToken, c.providerSpecificData, c.proxyOptions),
 };
 
 export async function getUsageForProvider(connection, proxyOptions = null) {