fix(ci): quote long 0x hex in workflows and add preflight guard

[MontrealAI]

Motivation

• GitHub Actions was failing to parse workflow YAML because long 0x… scalars were being treated as YAML integers (tag:yaml.org,2002:int) instead of strings.
• Demo workflows embed long hex private keys / addresses in env: blocks which must be quoted to avoid parser errors.
• A repo-level automated guard is needed to prevent future accidental unquoted hex values.

Description

• Quoted long hex scalars in demo and CI workflow files under .github/workflows/ (e.g. ci.yml, demo-asi-global.yml, demo-aurora.yml, demo-zenith-*), changing values like AURORA_WORKER_KEY: 0x… to AURORA_WORKER_KEY: '0x…'.
• Added scripts/ci/check-workflow-hex.js which scans .github/workflows/**/*.yml and fails if it finds unquoted : 0x[0-9a-fA-F]{16,} occurrences.
• Wired the guard into the local preflight pipeline by updating the ci:preflight script in package.json to run node scripts/ci/check-workflow-hex.js.
• Allowlisted the new script in .gitignore so it can be committed, and kept all changes minimal (only quoting and minor whitespace as needed).

Testing

• Ran npm install which completed successfully.
• Ran npm run ci:preflight and the toolchain, lock integrity, and the new workflow hex guard all passed (✅ Toolchain lock verification passed., ✅ All package-lock.json files are valid., Workflow YAML hex values are properly quoted.).
• Ran npm run ci:verify-toolchain and npm run ci:sync-contexts -- --check which both succeeded.
• Ran npm run ci:verify-contexts, npm run ci:verify-companion-contexts, and npm run ci:verify-summary-needs and all checks reported success.

---

Codex Task