fix(codex): add AskUserQuestion→request_user_input tool rewrite

Issue #1066 — Codex skills that call AskUserQuestion silently fail
in Default mode because Codex strips AskUserQuestion from the
tool schema and its equivalent (request_user_input) only works in
Plan mode.

The HostConfig interface already supports toolRewrites (gbrain, openclaw,
factory, hermes all use it). codex.ts was missing it.

Adding { 'AskUserQuestion': 'request_user_input' } to codex.ts so that
when gen-skill-docs.ts applies rewrites at generation time, any prompt
text referencing AskUserQuestion gets replaced with Codex's equivalent.

Note: this only handles the text rewrite. A full fix would also need
the Plan-mode gate in the preamble (Option 4 in #1066), but that requires
codex-side feature flag changes outside gstack's control.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

hosts/codex.ts

@@ -31,6 +31,10 @@ const codex: HostConfig = {
     { from: '.claude/skills', to: '.agents/skills' },
   ],
 
+  toolRewrites: {
+    'AskUserQuestion': 'request_user_input',
+  },
+
   suppressedResolvers: [
     'DESIGN_OUTSIDE_VOICES',  // design.ts:485 — Codex can't invoke itself
     'ADVERSARIAL_STEP',       // review.ts:408 — Codex can't invoke itself