Replaces ad-hoc Tailscale config tracking with a proper jobs system.
Jobs get their own nav page (master/detail layout), a dedicated DB
table, and full run history persisted forever. Tailscale connection
settings move from the Settings modal into the Jobs page. Registry
pattern makes adding future jobs straightforward.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Production images continue to display the semver (v1.x.x). Dev images
built by CI now receive BUILD_VERSION=dev-<7-char-sha> via a Docker ARG,
and app.js skips the v prefix for non-semver strings.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
