feat(antigravity,gemini): add Gemini 3.8 Flash support and bump IDE fingerprint to 2.11.0

Co-authored-by: Schnee111 <daffamaarif.dev@gmail.com>
Co-authored-by: AhooraZen <ahoora935137@gmail.com>
Co-authored-by: anojndr <anojndr@gmail.com>
Co-authored-by: Emirhan <emirhan551952@gmail.com>

tests/unit/antigravity-retry-hook.test.js

@@ -69,13 +69,13 @@ describe("antigravity computeRetryDelay hook (D3)", () => {
 
   it("registry uses the daily IDE cloudcode host and user agent", () => {
     expect(antigravity.transport.baseUrls).toEqual(["https://daily-cloudcode-pa.googleapis.com"]);
-    expect(antigravity.transport.headers["User-Agent"]).toBe("antigravity/ide/2.1.1 darwin/arm64");
+    expect(antigravity.transport.headers["User-Agent"]).toBe("antigravity/ide/2.11.0 darwin/arm64");
   });
 
   it("buildHeaders matches official IDE stream headers", () => {
     ag._lastSessionId = "sess-123";
     const h = ag.buildHeaders({ accessToken: "tok" }, true);
-    expect(h["User-Agent"]).toBe("antigravity/ide/2.1.1 darwin/arm64");
+    expect(h["User-Agent"]).toBe("antigravity/ide/2.11.0 darwin/arm64");
     expect(h["Content-Type"]).toBe("application/json");
     expect(h["Authorization"]).toBe("Bearer tok");
     expect(h).not.toHaveProperty("X-Machine-Session-Id");