security: replace hardcoded OAuth credentials with placeholders

- Replace Google OAuth ClientID/Secret with placeholder values
- Update test assertions to match new placeholder values

backend/internal/pkg/antigravity/oauth.go

@@ -23,7 +23,7 @@ const (
 	UserInfoURL  = "https://www.googleapis.com/oauth2/v2/userinfo"
 
 	// Antigravity OAuth 客户端凭证
-	ClientID = "1071006060591-tmhssin2h21lcre235vtolojh4g403ep.apps.googleusercontent.com"
+	ClientID = "YOUR_CLIENT_ID.apps.googleusercontent.com"
 
 	// AntigravityOAuthClientSecretEnv 是 Antigravity OAuth client_secret 的环境变量名。
 	AntigravityOAuthClientSecretEnv = "ANTIGRAVITY_OAUTH_CLIENT_SECRET"
@@ -53,7 +53,7 @@ const (
 var defaultUserAgentVersion = "1.20.5"
 
 // defaultClientSecret 可通过环境变量 ANTIGRAVITY_OAUTH_CLIENT_SECRET 配置
-var defaultClientSecret = "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"
+var defaultClientSecret = "YOUR_CLIENT_SECRET"
 
 func init() {
 	// 从环境变量读取版本号，未设置则使用默认值

backend/internal/pkg/antigravity/oauth_test.go

@@ -677,14 +677,14 @@ func TestConstants_值正确(t *testing.T) {
 	if UserInfoURL != "https://www.googleapis.com/oauth2/v2/userinfo" {
 		t.Errorf("UserInfoURL 不匹配: got %s", UserInfoURL)
 	}
-	if ClientID != "1071006060591-tmhssin2h21lcre235vtolojh4g403ep.apps.googleusercontent.com" {
+	if ClientID != "YOUR_CLIENT_ID.apps.googleusercontent.com" {
 		t.Errorf("ClientID 不匹配: got %s", ClientID)
 	}
 	secret, err := getClientSecret()
 	if err != nil {
 		t.Fatalf("getClientSecret 应返回默认值，但报错: %v", err)
 	}
-	if secret != "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" {
+	if secret != "YOUR_CLIENT_SECRET" {
 		t.Errorf("默认 client_secret 不匹配: got %s", secret)
 	}
 	if RedirectURI != "http://localhost:8085/callback" {

backend/internal/pkg/geminicli/constants.go

@@ -38,8 +38,8 @@ const (
 	// GeminiCLIOAuthClientID/Secret are the public OAuth client credentials used by Google Gemini CLI.
 	// They enable the "login without creating your own OAuth client" experience, but Google may
 	// restrict which scopes are allowed for this client.
-	GeminiCLIOAuthClientID     = "681255809395-oo8ft2oprdrnp9e3aqf6av3hmdib135j.apps.googleusercontent.com"
-	GeminiCLIOAuthClientSecret = "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"
+	GeminiCLIOAuthClientID     = "YOUR_CLIENT_ID.apps.googleusercontent.com"
+	GeminiCLIOAuthClientSecret = "YOUR_CLIENT_SECRET"
 
 	// GeminiCLIOAuthClientSecretEnv is the environment variable name for the built-in client secret.
 	GeminiCLIOAuthClientSecretEnv = "GEMINI_CLI_OAUTH_CLIENT_SECRET"