fix: remove dead shellQuote re-export from gcp/gcp.ts (#2551)

Dead backwards-compat re-export left over from the shellQuote
consolidation (PRs #2533, #2535, #2546). Zero consumers import
shellQuote from gcp/gcp.ts — all correctly import from shared/ui.ts.
Per CLAUDE.md: avoid backwards-compatibility hacks; delete unused code.

Agent: code-health

Co-authored-by: B <6723574+louisgv@users.noreply.github.com>
Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

packages/cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@openrouter/spawn",
-  "version": "0.17.1",
+  "version": "0.17.2",
   "type": "module",
   "bin": {
     "spawn": "cli.js"

packages/cli/src/gcp/gcp.ts

@@ -1081,8 +1081,3 @@ export async function destroyInstance(name?: string): Promise<void> {
   }
   logInfo(`Instance '${instanceName}' destroyed`);
 }
-
-// ─── Shell Quoting ──────────────────────────────────────────────────────────
-
-// shellQuote is now imported from shared/ui.ts and re-exported for backwards compat
-export { shellQuote } from "../shared/ui";