feat(layouts): switch track layout mid-practice and view stats per layout

A club can run one Open Practice all season and re-lay the track now and then.
Previously a session's layout was frozen at start and every training lap inherited
it, so a season-long practice stayed on its first layout forever, and changing layout
was hidden under Settings -> Appearance.

- Each practice lap now counts toward the layout active when it was driven; a running
  practice session moves onto a new layout when one is added
- "New layout" strip on Training stats, Race Day and the Dashboard, offered only around
  practice; a running race session blocks layout changes everywhere
- "Stats for" selector (current / older layout / before layouts / all layouts) on
  Training stats and in the driver's mobile profile (?layout= on the public API)
- A layout that has practice laps on it can no longer be deleted
- Fix: the buildDriverTrainingStats wrapper in app.js dropped extra arguments

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "rc-racecore",
-  "version": "1.24.0",
+  "version": "1.25.0",
   "private": true,
   "description": "RC RaceCore live timing and race control with AMMC ingest and SQLite persistence",
   "engines": {