feat(usage): surface Antigravity weekly quota alongside the 5-hour window (#4017) (#6818)

* feat(usage): surface Antigravity weekly quota alongside the 5-hour window (#4017)

Antigravity enforces both a 5-hour and a weekly usage limit, but the agy/antigravity
quota widget only exposed the 5-hour window. The weekly limit isn't in the per-model
retrieveUserQuota response already fetched — it lives in a separate, undocumented
retrieveUserQuotaSummary RPC that groups models into families (Gemini Models, Claude
and GPT models) with one weekly bucket per family.

Adds a self-contained usage/antigravityWeeklyQuota.ts leaf: a cached, best-effort
fetch of that RPC + a pure parser that extracts the weekly-labeled bucket per group
(window inferred from bucketId/displayName text, matching the reverse-engineered
shape documented by third-party Antigravity clients) into gemini_weekly/
claude_gpt_weekly quota entries, merged into the existing quotas map the widget
already renders generically. A failed/unavailable RPC never affects the existing
per-model quotas.

Live VPS validation attempt (192.168.0.15, real antigravity account): both
retrieveUserQuota and retrieveUserQuotaSummary currently return 429
RESOURCE_EXHAUSTED for that account, so the live response shape could not be
captured directly. The parser was instead validated via TDD against the bucket
shape documented by CodexBar (steipete/CodexBar), a third-party Antigravity client
that reverse-engineered the same RPC, and is defensive against both response
envelopes it has observed (top-level groups[] and nested quotaSummary.groups[]).

* chore(merge): re-sync with release/v3.8.47 (restore CHANGELOG, keep own bullet)

* chore(merge): re-sync with release/v3.8.47; move changelog bullet to changelog.d fragment (merge-storm proof)

src/app/(dashboard)/dashboard/usage/components/ProviderLimits/utils.tsx

@@ -34,6 +34,8 @@ const QUOTA_LABEL_MAP: Record<string, string> = {
   tokens: "Tokens",
   time_limit: "Time Limit",
   banked_reset_credits: "Banked Reset Credits",
+  gemini_weekly: "Gemini Weekly",
+  claude_gpt_weekly: "Claude & GPT Weekly",
 };
 
 function toRecord(value: unknown): Record<string, unknown> {