frontend: hover-revealed controls stay put where hovering is impossible (task 2697)

A finger cannot hover, and on a note card the hover toolbar is the only way to
pin, colour or archive — so on a phone those notes could not be acted on at all.
Same for deleting a checklist item, a saved view, an attachment or a preview.

Marked rather than rewritten inline: one `.hover-reveal` class on the five
elements and a single rule that says what it is for. The `group-hover:` reveal
stays in the markup because the trigger differs per component (named groups);
only the fallback is shared. `@media (hover: none)` asks the device directly,
which is more honest than inferring from viewport width — a narrow window on a
laptop still hovers, and a large tablet still doesn't. It sits after the Tailwind
directives so it beats the opacity-0/pointer-events-none utilities on source
order without !important.

Tap targets follow the same shape: p-1.5 around an 18px icon lands near 30px,
which is fine for a cursor and too small for a thumb. Bumped to 44px on coarse
pointers only, so desktop chrome doesn't inflate.

The drag grip is deliberately NOT revealed yet. Reordering still uses HTML5
drag-and-drop, which never fires from touch, so showing the handle would only
promise something that does nothing. It comes with the pointer-events rewrite.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

frontend/src/components/NoteCard.vue

@@ -277,9 +277,11 @@ onBeforeUnmount(() => document.removeEventListener("mousedown", onDocMousedown))
     <!-- Toolbar overlays the card's top-right on hover/focus as a floating pill
          (window-control style) instead of reserving a permanent row — so at rest
          the card is content-sized with even padding, not text pinned to the top
-         above an empty strip. -->
+         above an empty strip.
+         `hover-reveal`: on a device that can't hover this is the ONLY way to pin,
+         colour or archive a note, so there it stays visible (see style.css). -->
     <div
-      class="pointer-events-none absolute right-1.5 top-1.5 flex items-center gap-0.5 rounded-full bg-white/85 p-0.5 opacity-0 shadow-sm ring-1 ring-black/5 backdrop-blur-sm transition focus-within:pointer-events-auto focus-within:opacity-100 group-hover:pointer-events-auto group-hover:opacity-100 dark:bg-neutral-900/85 dark:ring-white/10"
+      class="hover-reveal pointer-events-none absolute right-1.5 top-1.5 flex items-center gap-0.5 rounded-full bg-white/85 p-0.5 opacity-0 shadow-sm ring-1 ring-black/5 backdrop-blur-sm transition focus-within:pointer-events-auto focus-within:opacity-100 group-hover:pointer-events-auto group-hover:opacity-100 dark:bg-neutral-900/85 dark:ring-white/10"
     >
       <template v-if="note.trashed">
         <button type="button" class="icon-btn" title="Restore" aria-label="Restore" @click="notes.restore(note.id)">