Add kit system, KitManager and Goblin kit

Introduce a full kit framework and supporting utilities.

- Add core kit API: Kit, Playstyle, ActiveAbility, PassiveAbility, AbilityResult, charge state and PlayerChargeData.
- Implement KitManager for registration, lobby selections, apply/remove/clear lifecycle and charge tracking.
- Add KitEventDispatcher listener to centralize kit event handling (interact, hits, move) and integrate passive/active hooks.
- Provide example kit implementations: GoblinKit (functional abilities) and TemplateKit (reference).
- Add utilities: ItemBuilder and WorldEditUtils (WorldEdit-based sphere creation).
- Integrate into plugin: SpeedHG now initialises KitManager, registers kits and KitEventDispatcher, applies kits at game start and clears on end.
- LanguageManager: add default message/list/component helpers.
- Build changes: bump Kotlin plugin to 2.2.0 and add WorldEdit compileOnly deps; also expose legacySerializer in Extensions.

These changes implement the kit feature set (items, abilities, charge/recharge flow) and wire it into the game lifecycle.

src/main/kotlin/club/mcscrims/speedhg/kit/Kit.kt

@@ -0,0 +1,87 @@
+package club.mcscrims.speedhg.kit
+
+import club.mcscrims.speedhg.kit.ability.ActiveAbility
+import club.mcscrims.speedhg.kit.ability.PassiveAbility
+import net.kyori.adventure.text.Component
+import org.bukkit.Material
+import org.bukkit.entity.Player
+
+/**
+ * Base class for every kit in SpeedHG.
+ *
+ * ## How to create a new kit
+ * 1. Extend this class.
+ * 2. Implement all abstract members.
+ * 3. For each [Playstyle], create a private inner class extending [ActiveAbility]
+ *    and another extending [PassiveAbility].
+ * 4. Return the correct instance from [getActiveAbility] / [getPassiveAbility]
+ *    using a `when(playstyle)` expression.
+ * 5. Register the kit via `plugin.kitManager.registerKit(YourKit())` in [SpeedHG.onEnable].
+ *
+ * See [TemplateKit] for a fully annotated example.
+ */
+abstract class Kit {
+
+	/** Unique snake_case identifier (e.g. `"warrior"`, `"archer"`). */
+	abstract val id: String
+
+	/** Coloured display name shown in the kit selection GUI. */
+	abstract val displayName: Component
+
+	/** Short lore lines shown on the item in the kit GUI. */
+	abstract val lore: List<String>
+
+	/** Icon used in the kit selection GUI. */
+	abstract val icon: Material
+
+	// -------------------------------------------------------------------------
+	//  Playstyle-specific abilities — implement with a `when` expression
+	// -------------------------------------------------------------------------
+
+	/**
+	 * Return the [ActiveAbility] for the given [playstyle].
+	 *
+	 * ```kotlin
+	 * override fun getActiveAbility(playstyle: Playstyle) = when (playstyle) {
+	 *     Playstyle.AGGRESSIVE -> AggressiveActive()
+	 *     Playstyle.DEFENSIVE  -> DefensiveActive()
+	 * }
+	 * ```
+	 *
+	 * **Performance note:** This is called frequently by [KitEventDispatcher].
+	 * Prefer returning a cached singleton (`private val aggressiveActive = AggressiveActive()`)
+	 * over allocating a new instance on each call.
+	 */
+	abstract fun getActiveAbility( playstyle: Playstyle ): ActiveAbility
+
+	/** Return the [PassiveAbility] for the given [playstyle]. Same caching advice applies. */
+	abstract fun getPassiveAbility( playstyle: Playstyle ): PassiveAbility
+
+	// -------------------------------------------------------------------------
+	//  Item distribution
+	// -------------------------------------------------------------------------
+
+	/**
+	 * Give the player their kit-specific items at game start (after teleportation).
+	 * The standard HG items (soup, compass, etc.) are already given by [GameManager].
+	 * Only add kit-exclusive items here.
+	 */
+	abstract fun giveItems( player: Player, playstyle: Playstyle )
+
+	// -------------------------------------------------------------------------
+	//  Lifecycle hooks (optional)
+	// -------------------------------------------------------------------------
+
+	/**
+	 * Called once per round when the kit is applied to [player].
+	 * Use for permanent potion effects, scoreboard objectives, repeating tasks, etc.
+	 * The matching [PassiveAbility.onActivate] is called immediately after this.
+	 */
+	open fun onAssign( player: Player, playstyle: Playstyle ) {}
+
+	/**
+	 * Called when the kit is removed (game over / round reset).
+	 * The matching [PassiveAbility.onDeactivate] is called immediately before this.
+	 */
+	open fun onRemove( player: Player ) {}
+}