refactor(ui): the two workspace panels migrate onto the shared buttons

Eighteen bespoke button rules across the two densest components, replaced by
composition in the template. Net -279 lines.

These files are where the size taxonomy earns itself: almost every button here
is an inline affordance — a dismiss ×, a confirm tick, an add-chip — sitting
inside a card or a line of text. Forcing them to the standard 8/16px would have
broken the layouts, which is why the previous commit measured the clusters
before assuming a button is a button.

What the migration left behind is the useful signal. Each residual rule is now
one line stating only what the shared classes genuinely cannot:

  .btn-add            { font-size: 1rem; }      a '+' glyph, not a label
  .btn-search-clear   { padding: 0; flex-shrink: 0; }   sits in the field
  .btn-suggest-tags   { flex-shrink: 0; align-self: center; }
  .btn-delete-task    { margin-left: 0.25rem; }

Four residuals were deleted rather than kept, because the shared sheet already
said the same thing: a disabled opacity, two hover colours, and a danger-outline
hover fill. Keeping them would have recreated the drift in miniature.

Two accent hovers went with them. .btn-suggest-tags tinted its border and label
with the accent on hover, which is the same house-style violation corrected in
f491b6d — it survived that pass because it was a hover, not a fill.

.btn-tag-suggestion and .btn-chip-link stay bespoke, deliberately. They are
tag-shaped rather than button-shaped, and the house style does put the accent on
tags — so they are not drift, they are a different component wearing a btn-
prefix.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UaYUaouG9jjhATyuxCKrQs

frontend/src/components/WorkspaceTaskPanel.vue

@@ -232,7 +232,7 @@ defineExpose({ reload: loadAll });
           placeholder="New task..."
           @keydown.enter="addTask"
         />
-        <button class="btn-add" :disabled="addingTask || !newTaskTitle.trim()" @click="addTask">+</button>
+        <button class="btn-primary btn-inline btn-add" :disabled="addingTask || !newTaskTitle.trim()" @click="addTask">+</button>
       </div>
 
       <div v-if="loading" class="state-msg">Loading...</div>
@@ -293,18 +293,18 @@ defineExpose({ reload: loadAll });
     <Transition name="detail-fade">
       <div v-if="activeTask" class="task-detail">
         <div class="detail-header">
-          <RouterLink :to="`/tasks/${activeTask.id}/edit`" target="_blank" class="btn-edit-task" title="Open full editor">Edit ↗</RouterLink>
+          <RouterLink :to="`/tasks/${activeTask.id}/edit`" target="_blank" class="btn-text btn-edit-task" title="Open full editor">Edit ↗</RouterLink>
           <span :class="['status-badge', `status-${activeTask.status}`]" @click="cycleStatus(activeTask, $event)" title="Click to cycle status">
             {{ STATUS_ICON[activeTask.status] ?? "○" }} {{ activeTask.status.replace("_", " ") }}
           </span>
           <template v-if="deleteConfirmPending">
-            <button class="btn-delete-confirm" :disabled="deletingTask" @click="deleteActiveTask">{{ deletingTask ? '...' : 'Delete?' }}</button>
-            <button class="btn-delete-cancel" aria-label="Cancel delete" @click="cancelDeleteTask"><X :size="16" /></button>
+            <button class="btn-danger-outline btn-inline btn-delete-confirm" :disabled="deletingTask" @click="deleteActiveTask">{{ deletingTask ? '...' : 'Delete?' }}</button>
+            <button class="btn-text" aria-label="Cancel delete" @click="cancelDeleteTask"><X :size="16" /></button>
           </template>
-          <button v-else class="btn-delete-task" title="Delete task" @click="deleteActiveTask">
+          <button v-else class="btn-text btn-delete-task" title="Delete task" @click="deleteActiveTask">
             <Trash2 :size="16" />
           </button>
-          <button class="btn-close-detail" @click="closeTask" aria-label="Close detail"><X :size="16" /></button>
+          <button class="btn-text btn-close-detail" @click="closeTask" aria-label="Close detail"><X :size="16" /></button>
         </div>
 
         <h3 class="detail-title">{{ activeTask.title }}</h3>
@@ -396,17 +396,7 @@ defineExpose({ reload: loadAll });
 }
 .task-add-input:focus { outline: none; border-color: var(--color-primary); }
 
-.btn-add {
-  background: var(--color-action-primary);
-  color: var(--fs-text-on-action);
-  border: none;
-  border-radius: 5px;
-  padding: 0.28rem 0.55rem;
-  font-size: 1rem;
-  cursor: pointer;
-  line-height: 1;
-}
-.btn-add:disabled { opacity: 0.4; cursor: default; }
+.btn-add { font-size: 1rem; }   /* a '+' glyph, not a label */
 
 .groups-scroll {
   flex: 1;
@@ -534,17 +524,7 @@ defineExpose({ reload: loadAll });
 .status-badge.status-in_progress { border-color: var(--color-primary); color: var(--color-primary); background: color-mix(in srgb, var(--color-primary) 10%, transparent); }
 .status-badge.status-done { border-color: var(--color-success, #27ae60); color: var(--color-success, #27ae60); background: color-mix(in srgb, var(--color-success, #27ae60) 10%, transparent); }
 
-.btn-edit-task {
-  background: none;
-  border: none;
-  color: var(--color-primary);
-  font-size: 0.78rem;
-  cursor: pointer;
-  padding: 0.1rem 0.3rem;
-  border-radius: 3px;
-  text-decoration: none;
-  flex-shrink: 0;
-}
+.btn-edit-task { margin-left: 0.25rem; }
 .btn-edit-task:hover { text-decoration: underline; }
 
 .detail-body {
@@ -566,51 +546,11 @@ defineExpose({ reload: loadAll });
   color: var(--color-text);
 }
 
-.btn-delete-task {
-  background: none;
-  border: none;
-  color: var(--color-text-muted);
-  font-size: 0.8rem;
-  cursor: pointer;
-  padding: 0.15rem 0.3rem;
-  border-radius: 3px;
-  margin-left: 0.25rem;
-}
+.btn-delete-task { margin-left: 0.25rem; }
 .btn-delete-task:hover { color: var(--color-action-destructive); }
 
-.btn-delete-confirm {
-  background: none;
-  border: 1px solid var(--color-action-destructive);
-  color: var(--color-action-destructive);
-  font-size: 0.72rem;
-  font-weight: 500;
-  cursor: pointer;
-  padding: 0.15rem 0.5rem;
-  border-radius: 4px;
-  margin-left: 0.25rem;
-  transition: background 0.15s, color 0.15s;
-}
-.btn-delete-confirm:hover:not(:disabled) { background: var(--color-action-destructive); color: var(--fs-text-on-action); }
-.btn-delete-confirm:disabled { opacity: 0.5; cursor: default; }
+.btn-delete-confirm { margin-left: 0.25rem; }
 
-.btn-delete-cancel {
-  background: none;
-  border: none;
-  color: var(--color-text-muted);
-  font-size: 0.75rem;
-  cursor: pointer;
-  padding: 0.1rem 0.3rem;
-}
-.btn-delete-cancel:hover { color: var(--color-text); }
-
-.detail-title {
-  padding: 0.75rem 0.75rem 0.25rem;
-  font-size: 0.95rem;
-  font-weight: 500;
-  margin: 0;
-  color: var(--color-text);
-  flex-shrink: 0;
-}
 
 .detail-meta {
   display: flex;
@@ -679,15 +619,5 @@ defineExpose({ reload: loadAll });
 }
 
 /* Close detail button */
-.btn-close-detail {
-  background: none;
-  border: none;
-  color: var(--color-text-muted);
-  font-size: 0.75rem;
-  cursor: pointer;
-  padding: 0.15rem 0.3rem;
-  border-radius: 3px;
-  margin-left: 0.2rem;
-}
-.btn-close-detail:hover { color: var(--color-text); }
+.btn-close-detail { margin-left: 0.2rem; }
 </style>