* Notice and status bar improvements
Status bar problems added in the same pass got the same `Date.now()` id and overwrote each other, so usually only one showed. Messages now fall back to their text as the id. The desktop status bar shows the most severe message with a count of the rest that opens a popover listing all of them, and the mobile drawer stacks them vertically instead of placing them side by side.
Dismissing a notice hid it for good, so a detector that restarted again after a dismissal was never shown. Dismiss is replaced by acknowledge, which hides a notice until it happens again, and mute, which hides it permanently. Kinds that never repeat (config and stream checks, the update notice) can only be muted. `reopen_at_count` is removed since acknowledge covers the failed login case.
* move camera CPU warnings to notices
High ffmpeg and detect CPU warnings sat in the status bar with no way to dismiss them. They're now `ffmpeg_high_cpu` and `detect_high_cpu` notices, raised per episode by the same tracker as skipped detections. Also stop failed login attempts held from before an acknowledgement from reopening the notice.
* fix mypy and handle missing cpu stats in notices
* add a notice registry and System Health tab
Problems Frigate detects on its own (ffmpeg crash loops, stuck detectors, failed model downloads, recordings deleted before their retention period) only ever existed as log lines. This adds a `NoticeRegistry` in the main process backed by two tables, an `update_notice` IPC topic so producers in other processes can reach it through the dispatcher, an admin-only API and websocket topic, and a Health tab that lists them. Kinds declare their own mode, severity, and category in one place: state notices are resolved by their producer, event notices are dismissed by the user.
* treat a prerelease as behind its final release
* fix notices clearing early
* rename menu items and update docs
* don't resolve the update notice on a failed version lookup
