Public release cleanup and build-flow hardening

[Obsecurus]

Summary

• remove tracked Namecheap DNS automation script and references from committed files
• keep Namecheap helper local-only via ignored .local/ path
• harden build-phase marker parsing on server/safety paths
• auto-switch UI to Dash when build starts (including fallback status sync)
• add regression tests for build marker variants and build trigger/build-status flow

Verification

• AUTO_GENERATE_CERTS=false node --test test.js
  • 92 passed, 0 failed

Notes

• main branch is protected and requires PR merge