fix: Preserve subscription intent through OAuth authentication flow

Users who selected the Pro plan from the subscription screen were landing
on the regular Claude interface instead of completing the upgrade after
signing in through Google OAuth. This fix ensures the subscription state
is maintained through the authentication flow.

CHANGELOG.md

@@ -5,6 +5,7 @@
 - Added env var `CLAUDE_CODE_ENABLE_TASKS`, set to `false` to keep the old system temporarily
 - Added shorthand `$0`, `$1`, etc. for accessing individual arguments in custom commands
 - Fixed crashes on processors without AVX instruction support
+- Fixed subscription intent not being preserved through OAuth authentication flow, causing users who selected the Pro plan to land on the regular interface instead of completing the upgrade after sign-in
 - Fixed dangling Claude Code processes when terminal is closed by catching EIO errors from `process.exit()` and using SIGKILL as fallback
 - Fixed `/rename` and `/tag` not updating the correct session when resuming from a different directory (e.g., git worktrees)
 - Fixed resuming sessions by custom title not working when run from a different directory