fix(report): move step-4 legend below curvature plot

dailywork_report/pathsmoothing_rep/01-local-g2-quintic-hermite-algorithm-visualization.html

@@ -57,7 +57,7 @@
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+        <g transform="translate(80 700)"><rect width="22" height="12" fill="#9aa6b5"/><text x="30" y="12" fill="#617086">原始粗路径</text><rect x="185" width="22" height="12" fill="#1976d2"/><text x="215" y="12" fill="#617086">窗口/约束</text><rect x="340" width="22" height="12" fill="#1d8a5b"/><text x="370" y="12" fill="#617086">已接受候选</text><rect x="535" width="22" height="12" fill="#bd7900"/><text x="565" y="12" fill="#617086">发布边界</text><rect x="705" width="22" height="12" fill="#c33b3b"/><text x="735" y="12" fill="#617086">拒绝/阻断</text></g>
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     </section>
     <p class="boundary">事实边界：正式发布流水线尚未接入；图中的绿色仅代表通过本演示中的典型质量门。</p>