Expose guided training exercises on the driver's mobile profile link

"Jämna varv" and "Stegträning" previously only lived on the admin
Training page. A driver's own personal mobile profile link now offers
the same self-service configure/start/stop flow already used for the
5-minute practice timer there, with live progress computed server-side
from the driver's own share token so raw lap rows and driver IDs never
reach the client.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "rc-racecore",
-  "version": "1.3.0",
+  "version": "1.4.0",
   "private": true,
   "description": "RC RaceCore live timing and race control with AMMC ingest and SQLite persistence",
   "engines": {