v3.0.0

First public release, under the public name PVE-UPS (technical identifiers — package,
paths, systemd units, env vars — deliberately stay pve-usv so in-place updates from 2.x
keep working).

Added

• Bilingual web UI: English (default) and German. The language is picked automatically
  from the browser language and is easy to extend
  (app/web/i18n/<lang>.js + one <script> tag).
• English user manual (manual.html) alongside the German one (handbuch.html), same
  structure and anchors; the ?-icon and all deep links open the manual matching the UI
  language.
• i18n consistency tests (tests/test_i18n.py): key parity between the dictionaries,
  placeholder parity, and referenced-key checks for index.html/app.js.
• Installation and updates via GitHub releases: install one-liner downloads
  install.sh from the latest release; the release tarball doubles as the update package
  for the web UI uploader.

Changed

• Breaking: all backend texts — event log entries, trigger reasons, webhook messages,
  API error details — are now uniformly English, regardless of the UI language.
• Webhook subject prefix is now [PVE-UPS].
• Visible product name is PVE-UPS (UI, documentation, webhook); internal names stay
  pve-usv.

Fixed

• The UPS card and the outage banner no longer show the time-based countdown once a UPS
  has triggered (battery low, runtime or charge threshold) — those conditions fire
  immediately and the ticking countdown wrongly suggested the shutdown would wait for
  it. The banner now also explains when triggered UPS are waiting for a host's
  AND/OR policy.

Removed

• Breaking: e-mail (SMTP) notifications. The webhook remains and covers notification
  needs; a legacy notifications.smtp config key is ignored on load and dropped on the
  next save.