style(post): polish post header + actions toolbar

- PostActions: every item is a rounded-full pill with subtle border;
  the three icon-only actions (share/copy/print) cluster in one
  segmented control with divider lines, count + reading-time stand
  alone left and right
- Share button only renders when `navigator.share` is available so
  desktop doesn't get a duplicate of "Copy link"
- All action buttons drop their inline labels and use `title=` +
  `aria-label` for tooltip-only access; copy still flips icon to a
  checkmark for 1.5s on success
- Empty comment state stacks vertically on mobile (icon above), goes
  horizontal + left-aligned on ≥sm
- Post header rebuilt: image fixed at 150x150 (no more mobile blow-up),
  right column is `flex flex-col gap-3` so date/tags/actions share one
  rhythm instead of ad-hoc margins
- Reading-time now also walks `row*Content` and pulls `content`/`body`/
  `text` strings — Termin-Posts with empty body but markdown rows now
  show a meaningful estimate

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/lib/components/Comments.svelte

@@ -400,8 +400,8 @@
     </div>
   {:else}
     {#if topLevel.length === 0}
-      <div class="flex flex-col items-center gap-2 py-8 text-center">
-        <Icon icon="mdi:comment-text-outline" class="size-10 text-zinc-300" />
+      <div class="flex flex-col items-center gap-2 py-8 text-center sm:flex-row sm:items-center sm:text-left sm:py-4 sm:gap-3">
+        <Icon icon="mdi:comment-text-outline" class="size-10 text-zinc-300 shrink-0" />
         <p class="text-sm text-zinc-500">{t(T.comments_empty)}</p>
       </div>
     {:else}