Fix character sheet holiday actions, remove dead holiday prompt, cap babysit counter

- Character sheet now checks isHolidayToday() for correct remaining
  action counts on holidays
- Remove renderAdvHolidaySecondPrompt (dead code after economy split)
  and its test
- Babysit harvest counter clamped to max to prevent exceeding budget

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/plugin/adventure_babysit.go

@@ -277,7 +277,14 @@ func (p *AdventurePlugin) runBabysitDaily(char *AdventureCharacter) {
 	result.TreasureFound = nil
 
 	// Mark action taken (babysit always uses a harvest action)
-	char.HarvestActionsUsed++
+	isHol, _ := isHolidayToday()
+	harvestMax := maxHarvestActions
+	if isHol {
+		harvestMax++
+	}
+	if char.HarvestActionsUsed < harvestMax {
+		char.HarvestActionsUsed++
+	}
 	char.ActionTakenToday = true
 	char.LastActionDate = time.Now().UTC().Format("2006-01-02")