feat(quota): add usage tracking for Groq

First slice of #3701: quota tracking for Groq via x-ratelimit-* response
headers on the models endpoint (no dedicated quota endpoint exists, and
reading usage costs zero tokens).

- usage/groq.js: parse request+token limit/remaining headers; Go-style
  duration reset headers ("2m59.56s") resolve to future timestamps;
  missing key/401/403 -> message, 2xx without headers -> soft
  "not tracked yet" with quotas:{}
- registry/groq.js: transport.usage.url (reuses validateUrl) +
  features {usage, usageApikey}
- services/usage.js: groq entry in USAGE_HANDLERS
- ProviderLimits/utils.js: parseQuotaData case (absolute used/total,
  codex/kiro style)
- tests: groq-usage.test.js (registry flags, header parsing, soft
  not-tracked path, missing key/401, parseQuotaData)

open-sse/services/usage.js

@@ -14,6 +14,7 @@ import { getCodeBuddyCnUsage, getCodeBuddyIntlUsage } from "./usage/codebuddy-cn
 import { getGrokCliUsage } from "./usage/grok-cli.js";
 import { getKimiUsage } from "./usage/kimi.js";
 import { getDeepseekUsage } from "./usage/deepseek.js";
+import { getGroqUsage } from "./usage/groq.js";
 import { getZedUsage } from "./usage/zed.js";
 import { resolveQoderCredentials } from "./qoderModels.js";
 import { getGlmUsage } from "./usage/glm.js";
@@ -55,6 +56,7 @@ const USAGE_HANDLERS = {
   "grok-cli": (c) => getGrokCliUsage(c.accessToken, c.providerSpecificData, c.proxyOptions),
   kimi: (c) => getKimiUsage(c.accessToken, c.apiKey, c.proxyOptions, c.providerSpecificData),
   deepseek: (c) => getDeepseekUsage(c.apiKey, c.proxyOptions),
+  groq: (c) => getGroqUsage(c.apiKey, c.proxyOptions),
   zed: (c) => getZedUsage(c.accessToken, c.providerSpecificData, c.proxyOptions),
 };