feat: duels player colors + elytra sub-modes (M-level)

- Add ParkourGenerator.selectBlockData() hook (forced course material);
  BlockSelector checks it first; SingleDuelsGenerator overrides to use the
  player's color (16 concrete colors) and forces only DEFAULT block type
- Elytra sub-modes: SpeedDemonGenerator (max-speed score), MinSpeedGenerator
  (min-speed check, reset on 6 slow ticks), TimeTrialGenerator (score cap),
  CloseGenerator (FLAT rings); + SpeedDemon/MinSpeed/TimeTrial/Close modes,
  registration, locales play.elytra.*, config mode-settings.*
- Config.getDouble(path, default) + ConfigAccessor overload
- checkstyle 0/0, PMD 0, build green

src/main/resources/locales/ru.yml

@@ -52,6 +52,26 @@ play:
       name: "&#00D4FF&lЭлитры"
       lore: "&#404040Летай сквозь кольца||&#404040на элитрах."
 
+    speeddemon:
+      material: "elytra"
+      name: "&#00D4FF&lСкорость-демон"
+      lore: "&#404040Разгонись до максимальной||&#404040скорости на элитрах."
+
+    minspeed:
+      material: "elytra"
+      name: "&#00D4FF&lМин. скорость"
+      lore: "&#404040Держи минимальную скорость||&#404040и лети как можно дальше."
+
+    timetrial:
+      material: "elytra"
+      name: "&#00D4FF&lГонка на время"
+      lore: "&#404040Достигни целевого счёта||&#404040как можно быстрее."
+
+    close:
+      material: "elytra"
+      name: "&#00D4FF&lБлизко"
+      lore: "&#404040Летай сквозь плоские кольца||&#404040расположенные вплотную."
+
   spectator:
     name: "&#FFFFFFНаблюдатель"