添加 hallmark 技能

skills/hallmark/references/components/c2-inline-form-as-cta.md

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+### C2 · Inline form-as-CTA
+The CTA *is* the form — a single email input with a "Submit →" beside it. No separate landing for sign-up.
+*Use when:* the action is collecting an email.
+*Don't confuse with:* C1 Outlined chip (which navigates, not submits).
+
+```html
+<form class="cta-form">
+  <label for="email" class="visually-hidden">Email</label>
+  <input id="email" type="email" placeholder="you@example.com" />
+  <button type="submit">Send →</button>
+</form>
+```
+```css
+.cta-form { display: grid; grid-template-columns: 1fr auto; border-bottom: 1px solid var(--color-ink); }
+.cta-form input { background: none; border: 0; padding: 0.7rem 0; min-height: 44px; }
+```