修正时间轴末帧，导出补阶跃与循环段边界关键帧

- 时间轴：末帧按时长实际覆盖的整数帧计算，修掉 Spine 时长小数舍入多出的一帧，B 端与回放自动停在最后一帧
- 导出：粒子死亡、骨骼池复用、拖尾假死复活处统一写 curve: stepped 硬切，避免死区插值出滑动轨迹
- 导出：循环持续在开始/循环/结束段边界（如 30f/110f）对所有动画通道补关键帧，便于在 Spine 中直接拆分
- 精简器支持阶跃段，阶跃区间内不再补出过渡关键帧
- 补充 test:spine-json 回归用例：骨骼池复用阶跃边界、循环段边界

scripts/verify-spine-json.mjs

@@ -3,6 +3,7 @@ import { build } from 'esbuild'
 const source = `
   import { buildSpineJson } from './src/export/spineJsonExporter.ts'
   import { validateSpineJson } from './src/export/spineJsonValidator.ts'
+  import { bakeLoopFrames } from './src/core/loopFrameBaker.ts'
 
   const resource = {
     id: 1, imageMode: 'single', sequenceFrames: [], textureName: 'star.png', textureFolder: '',
@@ -39,6 +40,93 @@ const source = `
       console.error('Spine ' + version + ': ' + (error instanceof Error ? error.message : String(error)))
     }
   }
+
+  // 假死 / 骨骼池复用：死区内的变换必须保持并硬切（阶跃关键帧），
+  // 不能在死区里插值出滑动轨迹，也不能在死区补出中间关键帧。
+  const poolState = (frame, spawnId, x, y) => ({
+    active: true, boneName: 'p_0', spawnId, resourceId: 1, imageFrameIndex: 0,
+    imageVisible: true, colorHex: 0xffffff, alpha: 1,
+    x, y, rotation: 0, scaleX: 1, scaleY: 1,
+    worldX: x, worldY: y, worldRotation: 0, worldScaleX: 1, worldScaleY: 1,
+  })
+  const poolFrames = Array.from({ length: 20 }, (_, frame) => {
+    if (frame <= 4) return [poolState(frame, 1, 10 + frame, 0)]
+    if (frame <= 9) return []
+    return [poolState(frame, 2, -200 + (frame - 10), 300)]
+  })
+  const poolSystem = {
+    id: 1, animation: 'animation', visible: true, frames: poolFrames,
+    config: {
+      name: 'verify', mode: 'burst', lifeMode: 'fixed', lifeMin: 1, lifeMax: 1, delay: 0,
+      imageResources: [resource], trail: false, trailResources: [],
+    },
+  }
+  const poolSettings = {
+    imagesPath: './images/', spineVersion: '4.2', keyframeCurve: 'bezier', fps: 30,
+    omitFps: false, integerFrameAlignment: true, bonePool: true,
+    excludeEmptyAnimations: false, fileName: 'verify.json',
+  }
+  const poolResult = buildSpineJson({ systems: [poolSystem], timeline, settings: poolSettings })
+  const poolBone = poolResult.json.animations.animation.bones._particle_000
+  const poolFramesAt = poolBone.translate.map((key) => Math.round(key.time * 30))
+  if (JSON.stringify(poolFramesAt) !== JSON.stringify([0, 4, 10, 19])) {
+    failures++
+    console.error('骨骼池复用：死区内不应插入过渡关键帧，实际为 ' + JSON.stringify(poolFramesAt))
+  }
+  const poolStepped = poolBone.translate.filter((key) => key.curve === 'stepped').map((key) => Math.round(key.time * 30))
+  if (JSON.stringify(poolStepped) !== JSON.stringify([4, 19])) {
+    failures++
+    console.error('骨骼池复用：死亡/复用边界应写阶跃关键帧，实际为 ' + JSON.stringify(poolStepped))
+  }
+
+  // 循环持续（开始 30f / 循环 80f / 结束 30f）：段边界 30f、110f 必须在所有动画通道上打关键帧。
+  const loopConfig = {
+    name: 'loop', mode: 'stream', streamBehavior: 'loop', rate: 4, delay: 0,
+    loopDurationFrames: 80,
+    generateLoopStartAnimation: true, loopStartUseCustomDuration: true, loopStartDurationFrames: 30,
+    generateLoopEndAnimation: true, loopEndUseCustomDuration: true, loopEndDurationFrames: 30,
+    lifeMode: 'fixed', lifeMin: 1, lifeMax: 1,
+    imageResources: [resource], trail: false, trailResources: [],
+  }
+  const loopEmitter = {
+    step: 0, activeCount: 1,
+    reset() { this.step = 0; this.activeCount = 1 },
+    restartEmissionCycle() { this.step = 0 },
+    update(_dt, mode) { if (mode === 'off') this.activeCount = 0; else this.step++; return this.capture() },
+    capture() {
+      return this.activeCount ? [{
+        active: true, boneName: 'p_0', spawnId: 1, resourceId: 1, imageFrameIndex: 0,
+        imageVisible: true, colorHex: 0xffffff, alpha: 1,
+        x: this.step, y: 0, rotation: 0, scaleX: 1, scaleY: 1,
+        worldX: this.step, worldY: 0, worldRotation: 0, worldScaleX: 1, worldScaleY: 1,
+      }] : []
+    },
+    apply() {},
+  }
+  const loopSystem = { id: 1, animation: 'animation', visible: true, config: loopConfig }
+  bakeLoopFrames(loopSystem, loopEmitter, 30, 141)
+  const loopResult = buildSpineJson({ systems: [loopSystem], timeline, settings: poolSettings })
+  const loopAnimation = loopResult.json.animations.animation
+  const boundaryFramesOf = (keys) => keys.filter((key) => {
+    const frame = Math.round(key.time * 30)
+    return frame === 30 || frame === 110
+  }).map((key) => Math.round(key.time * 30))
+  const expectedBoundaries = JSON.stringify([30, 110])
+  const loopBone = loopAnimation.bones._particle_000
+  const loopSlot = loopAnimation.slots._particle_000_image_normal
+  for (const channel of ['translate', 'rotate', 'scale']) {
+    if (JSON.stringify(boundaryFramesOf(loopBone[channel] || [])) !== expectedBoundaries) {
+      failures++
+      console.error('循环持续：骨骼 ' + channel + ' 通道缺少 30f/110f 段边界关键帧')
+    }
+  }
+  for (const channel of ['attachment', 'rgba']) {
+    if (JSON.stringify(boundaryFramesOf(loopSlot[channel] || [])) !== expectedBoundaries) {
+      failures++
+      console.error('循环持续：插槽 ' + channel + ' 通道缺少 30f/110f 段边界关键帧')
+    }
+  }
+
   if (failures) process.exitCode = 1
 `