Generalize Codex model proxy setup

[theFong]

Summary

• generalize the Codex proxy installer for any Responses-compatible model API while retaining Webster aliases and legacy-config migration
• discover models dynamically for each API key and generate complete strict Codex catalog metadata
• bind the proxy to localhost and add lifecycle-aware refresh guidance for managed, legacy SSH/npm, and Desktop-owned app-servers
• add an explicit, safety-validated --restart-app-server flow for legacy remote sessions

Validation

• proxy Node test suite: 10 passing
• ./test.sh
• bash syntax checks
• shellcheck codex-setup.sh
• actionlint .github/workflows/bootstrap.yml
• git diff --check