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

tests/unit/antigravity-usage-headers.test.js

@@ -4,8 +4,10 @@ const proxyAwareFetch = vi.fn(async (url) => ({
   ok: true,
   status: 200,
   json: async () => url.includes(":loadCodeAssist")
-    ? { cloudaicompanionProject: "project-1", currentTier: { name: "Pro" } }
-    : { models: {} },
+    ? { cloudaicompanionProject: "project-1", currentTier: { name: "Pro" }, paidTier: { id: "g1-pro-tier", name: "Google AI Pro" } }
+    : url.includes(":retrieveUserQuotaSummary")
+      ? { groups: [] }
+      : { models: {} },
   text: async () => "{}",
 }));
 
@@ -21,7 +23,8 @@ describe("Antigravity usage headers", () => {
 
     await getAntigravityUsage("access-token", {});
 
-    expect(proxyAwareFetch).toHaveBeenCalledTimes(2);
+    // loadCodeAssist + fetchAvailableModels + retrieveUserQuotaSummary
+    expect(proxyAwareFetch).toHaveBeenCalledTimes(3);
     for (const [, options] of proxyAwareFetch.mock.calls) {
       expect(options.headers["User-Agent"]).toBe("antigravity/ide/2.11.0 darwin/arm64");
       expect(options.headers).not.toHaveProperty("x-request-source");