fix(adapters/gemini-local): address PR review feedback

- Update stale doc comment in index.ts to reflect direct ~/.gemini/skills/
  injection instead of tmpdir approach
- Remove bare GEMINI_API_KEY/GOOGLE_API_KEY from auth regex to prevent
  false positives when those strings appear in assistant output
- Align hello probe sandbox/approvalMode flags with execute.ts

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

packages/adapters/gemini-local/src/server/execute.ts

@@ -384,7 +384,7 @@ export async function execute(ctx: AdapterExecutionContext): Promise<AdapterExec
       signal: attempt.proc.signal,
       timedOut: false,
       errorMessage: (attempt.proc.exitCode ?? 0) === 0 ? null : fallbackErrorMessage,
-      errorCode: authMeta.requiresAuth ? "gemini_auth_required" : null,
+      errorCode: (attempt.proc.exitCode ?? 0) !== 0 && authMeta.requiresAuth ? "gemini_auth_required" : null,
       usage: attempt.parsed.usage,
       sessionId: resolvedSessionId,
       sessionParams: resolvedSessionParams,