web: shared note actions, reminder chips, page header, formatters and settings seam

From the audit (#5179, web half).

- NoteActions: share, pin, archive and trash (restore and delete forever
  when trashed), as both the card and the editor offer them. The editor's
  history toggle goes in its slot, and it closes on `acted`.
- ReminderActions: the Done / 1h / 1d chips on the card and in the editor,
  which are now the same chips.
- PageHeader: the back-to-board header that Settings, Sync and Linked
  devices each wrote out, now with a `back` icon from the shared set.
- notes/datetime: formatShortDateTime (was formatReminder and the editor's
  revLabel) and formatDateTime (the two `fmt` copies).
- notes/colors: labelDotClasses (the sidebar's and the tag manager's
  labelDot).
- Drawer links use exact-active-class instead of route.name ternaries.
- BoardView binds its three grids from one gridBinds object.
- Settings goes through repo.settings (rest, plus a local adapter that
  answers "needs a server") and shows load failures through AsyncState.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/views/BoardView.vue

@@ -281,6 +281,17 @@ async function onDrop(targetId: string) {
   order.splice(toIdx, 0, from);
   await notes.reorder(order);
 }
+
+/** What every grid on this board takes besides its notes: the keyboard focus, and
+ * opening and reordering cards. */
+const gridBinds = computed(() => ({
+  activeId: focusedId.value,
+  reorderable: true,
+  onOpen: openEditor,
+  onDragstart: onDragStart,
+  onDragend: onDragEnd,
+  onDrop,
+}));
 </script>
 
 <template>
@@ -340,42 +351,17 @@ async function onDrop(targetId: string) {
       <template v-if="isMainBoard">
         <section v-if="pinnedNotes.length">
           <h2 class="mb-2 text-xs font-semibold uppercase tracking-wide text-neutral-400">Pinned</h2>
-          <NoteGrid
-            :notes="pinnedNotes"
-            :active-id="focusedId"
-            reorderable
-            @open="openEditor"
-            @dragstart="onDragStart"
-            @dragend="onDragEnd"
-            @drop="onDrop"
-          />
+          <NoteGrid :notes="pinnedNotes" v-bind="gridBinds" />
         </section>
         <section v-if="otherNotes.length" :class="pinnedNotes.length ? 'mt-8' : ''">
           <h2 v-if="pinnedNotes.length" class="mb-2 text-xs font-semibold uppercase tracking-wide text-neutral-400">
             Others
           </h2>
-          <NoteGrid
-            :notes="otherNotes"
-            :active-id="focusedId"
-            reorderable
-            @open="openEditor"
-            @dragstart="onDragStart"
-            @dragend="onDragEnd"
-            @drop="onDrop"
-          />
+          <NoteGrid :notes="otherNotes" v-bind="gridBinds" />
         </section>
       </template>
 
-      <NoteGrid
-        v-else
-        :notes="notes.items"
-        :active-id="focusedId"
-        reorderable
-        @open="openEditor"
-        @dragstart="onDragStart"
-        @dragend="onDragEnd"
-        @drop="onDrop"
-      />
+      <NoteGrid v-else :notes="notes.items" v-bind="gridBinds" />
       </template>
     </AsyncState>
   </div>