fix(codex): remove invalid resume flags

[Gujiassh]

Summary

• remove -C and -s from the codex exec resume consult-mode command in the Codex skill
• switch the resumed-session example to -c "sandbox_mode="read-only"", which the resume subcommand actually accepts
• document that resume inherits working directory from the current shell/session context

Why

Issue #1258 reports that /codex consult-mode resume currently documents flags that codex exec resume rejects on codex-cli 0.125.0, causing the skill flow to fail with exit 2 instead of resuming the session.

Testing

• bun run gen:skill-docs
• bun test test/skill-validation.test.ts

---

^{Need help on this PR? Tag @codesmith with what you need.}

• Let Codesmith autofix CI failures and bot reviews

[garrytan]

Closing in favor of #1270 (also by @jbetala7) which lands the same fix plus a regression test. Merged as part of the v1.30.0.0 fix wave (#1391). Thanks for the contribution!