fix(form): shrink sm inputs to text-xs, align consent checkbox top

- TextInput/Textarea size="sm": text-xs, tighter padding (h-9, px-2.5
  py-1.5) so placeholder/value match label scale.
- Checkbox: new size prop (sm = h-4 w-4 + text-xs leading-snug).
  Switched container to flex/items-start so multi-line labels align
  with checkbox top instead of vertically centering and pushing the
  box halfway down the paragraph.
- ContactForm: consent checkbox uses size="sm"; privacy note + error
  hint at text-[0.7rem] leading-snug to match.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/components/internal/ContactFormComponent.svelte

@@ -266,14 +266,15 @@
 
     <div data-field="consent" class="pt-1">
       <Checkbox
+        size="sm"
         name="consent"
         bind:checked={consent}
         label={t(T.contact_label_consent)}
       />
       {#if showError("consent")}
-        <p class="mt-1 text-[0.75rem] text-error" role="alert">{showError("consent")}</p>
+        <p class="mt-1 text-[0.7rem] text-error" role="alert">{showError("consent")}</p>
       {/if}
-      <p class="mt-1 text-xs text-stein-500">{t(T.contact_privacy_note)}</p>
+      <p class="mt-1 text-[0.7rem] leading-snug text-stein-500">{t(T.contact_privacy_note)}</p>
     </div>
 
     {#if TURNSTILE_ENABLED}