feat(antigravity): add weekly quota tracking and free-tier handling (#3892)

tests/unit/antigravity-quota-gemini-3.7.test.js

@@ -4,7 +4,7 @@ const proxyAwareFetch = vi.fn(async (url) => ({
   ok: true,
   status: 200,
   json: async () => url.includes(":loadCodeAssist")
-    ? { cloudaicompanionProject: "project-1", currentTier: { name: "Pro" } }
+    ? { cloudaicompanionProject: "project-1", currentTier: { name: "Pro" }, paidTier: { id: "g1-pro-tier", name: "Google AI Pro" } }
     : {
         models: {
           "gemini-3.7-flash-high": {