feat(config): add user reviews to docs and improve Antigravity provider config

- Add user reviews section to READMEs (EN, KO, JA, ZH-CN)
- Update Antigravity request.ts: change default model from gemini-3-pro-preview to gemini-3-pro-high
- Enhance config-manager.ts: add full model specs (name, limit, modalities) to provider config
- Add comprehensive test suite for config-manager (config-manager.test.ts)

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src/cli/config-manager.test.ts

@@ -0,0 +1,36 @@
+import { describe, expect, test } from "bun:test"
+
+import { ANTIGRAVITY_PROVIDER_CONFIG } from "./config-manager"
+
+describe("config-manager ANTIGRAVITY_PROVIDER_CONFIG", () => {
+  test("Gemini models include full spec (limit + modalities)", () => {
+    const google = (ANTIGRAVITY_PROVIDER_CONFIG as any).google
+    expect(google).toBeTruthy()
+
+    const models = google.models as Record<string, any>
+    expect(models).toBeTruthy()
+
+    const required = [
+      "gemini-3-pro-high",
+      "gemini-3-pro-medium",
+      "gemini-3-pro-low",
+      "gemini-3-flash",
+      "gemini-3-flash-lite",
+    ]
+
+    for (const key of required) {
+      const model = models[key]
+      expect(model).toBeTruthy()
+      expect(typeof model.name).toBe("string")
+      expect(model.name.includes("(Antigravity)")).toBe(true)
+
+      expect(model.limit).toBeTruthy()
+      expect(typeof model.limit.context).toBe("number")
+      expect(typeof model.limit.output).toBe("number")
+
+      expect(model.modalities).toBeTruthy()
+      expect(Array.isArray(model.modalities.input)).toBe(true)
+      expect(Array.isArray(model.modalities.output)).toBe(true)
+    }
+  })
+})