feat(board): inline delete confirmation + a11y polish

Replace window.confirm with an inline Delete? / Cancel / Confirm flow on
post cards. Add focus-visible outlines, initials in avatar placeholders,
and promote post/form titles from h3 to h2 for heading order.

app/pages/board.vue

@@ -73,8 +73,11 @@
             :channels="channels"
             :tags="cooperativeTags"
             :editable="isAuthor(post)"
+            :pending-delete="pendingDeleteId === post._id"
             @edit="handleEdit"
-            @delete="handleDelete"
+            @delete="requestDelete"
+            @confirm-delete="confirmDelete"
+            @cancel-delete="cancelDelete"
           />
         </div>
       </template>
@@ -103,6 +106,7 @@ const activeTagFilter = ref(null)
 
 const showForm = ref(false)
 const editingPost = ref(null)
+const pendingDeleteId = ref(null)
 
 const currentMemberId = computed(() => memberData.value?._id || null)
 
@@ -144,12 +148,18 @@ const handleEdit = (post) => {
   }
 }
 
-const handleDelete = async (post) => {
-  if (typeof window === 'undefined') return
-  const ok = window.confirm('Delete this post? This cannot be undone.')
-  if (!ok) return
+const requestDelete = (post) => {
+  pendingDeleteId.value = post._id
+}
+
+const cancelDelete = () => {
+  pendingDeleteId.value = null
+}
+
+const confirmDelete = async (post) => {
   try {
     await deletePost(post._id)
+    pendingDeleteId.value = null
   } catch (err) {
     toast.add({
       title: 'Failed to delete post',
@@ -219,6 +229,10 @@ onMounted(async () => {
   border-style: solid;
   background: rgba(154, 116, 32, 0.08);
 }
+.new-post-btn:focus-visible {
+  outline: 2px dashed var(--candle);
+  outline-offset: 2px;
+}
 
 /* ---- TAGS DRAWER ---- */
 .tags-drawer-toggle {
@@ -242,6 +256,10 @@ onMounted(async () => {
   border-color: var(--candle-faint);
   color: var(--text);
 }
+.drawer-btn:focus-visible {
+  outline: 2px dashed var(--candle);
+  outline-offset: 2px;
+}
 .tag-count-badge {
   font-size: 9px;
   background: var(--candle-faint);
@@ -288,6 +306,11 @@ onMounted(async () => {
   color: var(--candle);
   background: rgba(154, 116, 32, 0.08);
 }
+.skills-bar .skill-tag:focus-visible,
+.more-btn:focus-visible {
+  outline: 2px dashed var(--candle);
+  outline-offset: 2px;
+}
 .more-btn {
   font-family: "Commit Mono", monospace;
   font-size: 10px;
@@ -355,11 +378,14 @@ onMounted(async () => {
   }
 }
 @media (max-width: 768px) {
+  .action-bar {
+    padding: 12px 16px;
+  }
   .tags-drawer-toggle {
-    padding: 8px 20px;
+    padding: 8px 16px;
   }
   .skills-bar {
-    padding: 10px 20px;
+    padding: 10px 16px;
   }
   .post-grid,
   .form-wrapper {