feat: add Elytra mode (basic S-level)

- elytra/section/: ElytraSection (5 knots + cubic spline via commons-math3),
  ElytraKnotDirector (dx~N(75,15), dy bias, dz~N(0,35)), ElytraPointType
  (CIRCLE Bresenham / FLAT), ClientBlockChanger (client-side sendBlockChanges,
  forward-limit min(vd,8))
- elytra/generator/ElytraGenerator extends ParkourGenerator: own tick() (score by
  velocity.x while gliding, section lifecycle, fall detection, sustained boost in
  ascending sections), reset, spawn with elytra
- elytra/mode/ElytraMode: registered in Modes/PluginBootstrap, locale items ru/en
- build.gradle: commons-math3 3.6.1 + relocate
- checkstyle 0/0, PMD 0, build green (tests + shadowJar)

build.gradle.kts

@@ -93,6 +93,7 @@ dependencies {
     implementation("org.bstats:bstats-bukkit:3.2.1")
     implementation("com.zaxxer:HikariCP:5.1.0")
     implementation("com.mysql:mysql-connector-j:8.3.0")
+    implementation("org.apache.commons:commons-math3:3.6.1")
     compileOnly("com.sk89q.worldedit:worldedit-core:7.3.6")
     compileOnly("com.sk89q.worldedit:worldedit-bukkit:7.3.6")
 
@@ -122,6 +123,7 @@ tasks.shadowJar {
     relocate("io.papermc.lib", "dev.loki.loparkour.lib.paperlib")
     relocate("com.google.gson", "dev.loki.loparkour.lib.gson")
     relocate("org.bstats", "dev.loki.loparkour.lib.bstats")
+    relocate("org.apache.commons.math3", "dev.loki.loparkour.lib.commonsmath3")
 
     // Don't minimize - causes issues with Caffeine's dynamically generated classes
     // minimize {