添加 hallmark 技能

skills/hallmark/references/components/s5-bottom-anchored.md

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+### S5 · Bottom-anchored
+The label or heading sits *below* the section's content. Inverts hierarchy.
+*Use when:* the content is the primary act and the label is a footer to it.
+*Don't confuse with:* S1 Left-margin (which leads with the label).
+
+```html
+<section>
+  <div class="content">…</div>
+  <p class="num-label">— end of 02</p>
+</section>
+```
+
+---