Add per-driver live stats for timed practice sessions

docs/javascript-architecture.md

@@ -465,6 +465,7 @@ Owns:
 - fetching only `/public-training/api/:shareToken`
 - rendering one driver's sanitized statistics, goals, rewards, and daily history
 - local 20-minute practice timer with 10-minute push/control phases
+- token-scoped start-age and bounded-window polling for aggregate lap count, best lap, and average during the personal timer; using an age avoids mobile/server clock-skew errors and the bounded window freezes results after the timer finishes
 - Swedish/English copy selected by `lang` query or browser locale
 
 Important isolation:
@@ -472,6 +473,7 @@ Important isolation:
 - does not call `/api/state`
 - does not mutate backend or race state
 - timer state is stored in the mobile browser under a token-scoped localStorage key
+- session-window responses contain aggregates only; individual lap rows and timestamps are not exposed
 
 ### `src/public_training.css`
 Type:
@@ -1904,6 +1906,7 @@ Sanitized response fields:
 - selected driver display name, class, and brand
 - numeric club rank without other driver names
 - aggregate totals, best/average time, consistency, controlled streak, and daily summaries
+- optional `currentSession` aggregates when a valid start age (or backward-compatible recent `since` timestamp) is supplied
 - next automatic milestone
 - recommendation level and target lap
 - selected driver's goal titles, reward text, progress, and claimed state