性能（BurstDrive）：跳过未注册特效的每 tick 查询

根因：
BurstDrive 对每把 SlashBlade 的服务器更新都会读取状态并调用通用特效查询；没有 BurstDrive 注册项的刀也会走到该路径，通用查询还会懒创建空的 SB.SEffect 复合标签。

改动：
在保留根 NBT 获取后，先检查 SB.SEffect 复合标签及 BurstDrive 键。未注册或空标签直接返回；已注册的键继续调用既有 isEffective、损坏状态、粒子和攻击代码。

契约：
已注册的 BurstDrive 仍由原有通用特效 API 决定有效性，包含零值、异常数值类型、玩家状态和后续攻击时序。未注册或空特效标签本来只能得到 None；现在不再为其调用通用查询，也不再写入语义为空的 SB.SEffect 子标签。

性能：
静态计数：未注册刀每个服务器更新从 1 次通用 isEffective/getSpecialEffect 查询及其潜在空子标签写入，降为 2 次 NBT 键存在性检查后返回。已注册刀路径不变。未进行实际服务器性能测量。

验证：
通过 tests/regression/burst_drive_effect_registration_regression.py，检查过滤顺序及空、已注册和异常数值键的分流；通过 ./gradlew --no-daemon compileJava reobfJar --console=plain 与 git diff --check。未在 Forge 多人运行时验证粒子与攻击体验。

Refs: #2

src/main/java/mods/flammpfeil/slashblade/kirisaya/specialeffect/BurstDrive.java

@@ -46,6 +46,7 @@ import net.minecraft.world.World;
 public class BurstDrive
 implements ISpecialEffect {
     static final String EffectKey = "BurstDrive";
+    private static final String SPECIAL_EFFECTS_TAG = "SB.SEffect";
 
     private boolean useBlade(ItemSlashBlade.ComboSequence sequence) {
         if (sequence.useScabbard) {
@@ -66,6 +67,13 @@ implements ISpecialEffect {
         EntityPlayer player = (EntityPlayer)event.entity;
         ItemStack blade = event.blade;
         NBTTagCompound tag = ItemSlashBlade.getItemTagCompound((ItemStack)blade);
+        if (!tag.hasKey(SPECIAL_EFFECTS_TAG, 10)) {
+            return;
+        }
+        NBTTagCompound specialEffects = tag.getCompoundTag(SPECIAL_EFFECTS_TAG);
+        if (!specialEffects.hasKey(EffectKey)) {
+            return;
+        }
         if (ItemSlashBlade.IsBroken.get(tag).booleanValue()) {
             return;
         }

tests/regression/burst_drive_effect_registration_regression.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+"""Regression checks for BurstDrive's registration prefilter.
+
+This is a source-level guard test: Forge 1.7.10 event dispatch is not available
+in the build environment.  It protects the intended ordering and the two
+semantics that matter for the fast path: absent or empty effect data cannot
+activate BurstDrive, while registered data still reaches isEffective().
+"""
+
+from pathlib import Path
+
+
+SOURCE = Path(__file__).parents[2] / (
+    "src/main/java/mods/flammpfeil/slashblade/kirisaya/specialeffect/BurstDrive.java"
+)
+
+
+def registration_prefilter(effect_data):
+    """Mirror the new guard, where None denotes a missing/non-compound tag."""
+    if effect_data is None:
+        return False
+    return "BurstDrive" in effect_data
+
+
+def main():
+    source = SOURCE.read_text(encoding="utf-8")
+    compound_guard = 'if (!tag.hasKey(SPECIAL_EFFECTS_TAG, 10))'
+    effect_guard = 'if (!specialEffects.hasKey(EffectKey))'
+    broken_read = 'if (ItemSlashBlade.IsBroken.get(tag).booleanValue())'
+    effectiveness = 'switch (SpecialEffects.isEffective('
+
+    assert compound_guard in source
+    assert effect_guard in source
+    assert source.index(compound_guard) < source.index(broken_read)
+    assert source.index(effect_guard) < source.index(effectiveness)
+
+    # Both cases historically resolve to SpecialEffects.Result.None; neither
+    # may reach the broken-state, effect lookup, particles, or attack path.
+    assert not registration_prefilter(None)
+    assert not registration_prefilter({})
+
+    # A present key deliberately continues through the existing API, including
+    # its handling of zero, malformed numeric data, and player/equipment state.
+    assert registration_prefilter({"BurstDrive": 0})
+    assert registration_prefilter({"BurstDrive": 1})
+    assert registration_prefilter({"BurstDrive": "unexpected-type"})
+
+    print("burst-drive-registration-prefilter-regression-ok")
+
+
+if __name__ == "__main__":
+    main()