Add moving a driver between qualifying heats

The user asked whether a lone driver left in the last heat (e.g. 7
drivers at 3 per heat) could be moved into another heat manually.
Investigated first: neither "Reseed" (redistributes every not-yet-run
heat by current standings, not a targeted move) nor the grid editor
(reorders start position within one heat, never moves a driver
between heats) could do this - there was genuinely no path to it.

moveDriversIntoQualifyingHeat (src/event_race_logic.js) adds the same
"checking them elsewhere is the move" pattern already used for team
rosters: a new driver checklist on the qualification session edit
form pulls a checked driver out of whichever other heat they're
currently on, scoped to the same round only ("Q2 H2" never touches
"Q1"/"Q3", since heat composition can legitimately differ round to
round after a reseed). The checklist names the driver's current heat
before saving, mirroring the team-roster warning.

Also confirmed, per the user's earlier questions, already correct
with no changes needed: practice's per-driver "best 3 laps"/"best
5-minute result" stats, and that heats are already seeded fastest-
first from practice results. Flagged one real, deliberately unbuilt
gap while investigating: a true per-driver rolling "5 minutes from
your own first crossing" qualifying *heat* clock isn't supported -
only the practice stats work that way today.

Verified with new unit tests for moveDriversIntoQualifyingHeat and
the extracted parseQualifyingHeatName helper, and a real headless-
browser run reproducing the exact reported scenario end to end
through the actual UI.

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

CHANGELOG.md

@@ -8,6 +8,12 @@ The application version is maintained in `package.json` and displayed in the adm
 
 No changes recorded yet.
 
+## 1.11.0 - 2026-09-10
+
+### Added
+
+- A driver left alone in the last qualifying heat (e.g. 7 drivers at 3 per heat) can now be moved into another heat directly - edit a heat and tick the driver on, and they're automatically moved out of whichever heat they were on before, with a warning shown before you save.
+
 ## 1.10.3 - 2026-09-10
 
 ### Fixed