fix(antigravity): add aicode OAuth scope for voice transcription support

[icarogamatos]

Problem Description

When authenticating Google Antigravity accounts through Cockpit Tools, standard text prompts and code assistance work as expected, but the built-in Live Voice Transcription (streamAudioTranscription via the microphone button or Ctrl+Shift+M) fails immediately within ~1 second.

Inspecting the Antigravity runtime console logs reveals:

[AudioStreaming] Stream error: ConnectError: [internal] internal: failed to receive setup response from backend: rpc error: code = PermissionDenied desc = Request had insufficient authentication scopes. (error ID: ...)
[AudioStreaming] Failed to start: ConnectError: [internal] internal: failed to receive setup response from backend: rpc error: code = PermissionDenied desc = Request had insufficient authentication scopes.

Root Cause

In Cockpit Tools, the Google OAuth authorization URL (get_auth_url) requested only 6 scopes:

• openid
• https://www.googleapis.com/auth/cloud-platform
• https://www.googleapis.com/auth/userinfo.email
• https://www.googleapis.com/auth/userinfo.profile
• https://www.googleapis.com/auth/cclog
• https://www.googleapis.com/auth/experimentsandconfigs

Antigravity 2.0+ uses bidirectional gRPC audio streaming with Google's backend API, which strictly requires the Cloud Code AI scope: https://www.googleapis.com/auth/aicode. Because tokens minted by Cockpit Tools lacked this scope, Google's backend immediately rejected the audio stream with PermissionDenied: Request had insufficient authentication scopes.

Changes Made

Added "https://www.googleapis.com/auth/aicode" to the OAuth scopes list in:

• src-tauri/src/modules/oauth.rs
• crates/cockpit-core/src/modules/oauth.rs

Verification

• Verified that Google's OAuth consent endpoint with Client ID 1071006060591-tmhssin2h21lcre235vtolojh4g403ep.apps.googleusercontent.com accepts and grants https://www.googleapis.com/auth/aicode.
• Tested the authorization flow on Windows 11 with Antigravity v2.12.0:
  • Token exchange succeeded with aicode included in the granted scopes.
  • Live audio transcription / voice memo starts and transcribes spoken audio correctly in real-time.
  • Text prompts, agent actions, and account switching continue to function normally.