fix(gemini-cli): use backend project ID from onboarding response

- Simplify project ID selection to always use the backend project ID returned by Gemini onboarding
- Update Gemini CLI version from 0.31.0 to 0.34.0
- Add 'terminal' to User-Agent string for better client identification

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/misc/header_utils.go

@@ -12,7 +12,7 @@ import (
 
 const (
 	// GeminiCLIVersion is the version string reported in the User-Agent for upstream requests.
-	GeminiCLIVersion = "0.31.0"
+	GeminiCLIVersion = "0.34.0"
 
 	// GeminiCLIApiClientHeader is the value for the X-Goog-Api-Client header sent to the Gemini CLI upstream.
 	GeminiCLIApiClientHeader = "google-genai-sdk/1.41.0 gl-node/v22.19.0"
@@ -46,7 +46,7 @@ func GeminiCLIUserAgent(model string) string {
 	if model == "" {
 		model = "unknown"
 	}
-	return fmt.Sprintf("GeminiCLI/%s/%s (%s; %s)", GeminiCLIVersion, model, geminiCLIOS(), geminiCLIArch())
+	return fmt.Sprintf("GeminiCLI/%s/%s (%s; %s; terminal)", GeminiCLIVersion, model, geminiCLIOS(), geminiCLIArch())
 }
 
 // ScrubProxyAndFingerprintHeaders removes all headers that could reveal