feat(design): surface phase PR 1 — Lucide icon migration + scale enforcement

Replaces every hand-inlined SVG in the chrome (60 across 15 files)
with Lucide components. Snaps icon sizes to the doc's 16/24 scale —
all icons in this pass land at 16. AppLogo wordmark stays as the
legitimate "custom app icon" exception per the doc; GraphView's <svg>
mount point for D3 stays as well.

Replaces emoji-as-icons in clear button-affordance cases with their
Lucide equivalents: ✕ → X (close/dismiss buttons across 8 files), ✓ →
Check (ProjectView task-advance button), 🎤 → Mic (ChatPanel voice
CTA), 📎 → Paperclip (ChatView context toggle), &uarr; → ArrowUp
(ChatInputBar Send), &times; → X (ChatPanel context-note remove), ☀/☾
→ Sun/Moon (AppHeader theme toggle).

Inline emoji punctuation in textual confirmation copy ("Saved ✓",
"Created ✓", `done: "✓"` status maps, `'✓' : '📄'` interpolations)
is left for surface-phase voice/tone touchups — replacing requires
structural template changes and is best done per-component.

Stroke weight stays at Lucide's default 2px; tightening to the doc's
1.5/1 is deferred per the surface-phase spec (option ii: drop-in +
scale enforcement).

Adds lucide-vue-next ^0.469.0 to frontend/package.json. Docker
rebuild handles the install.

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

frontend/src/components/WorkspaceTaskPanel.vue

@@ -5,6 +5,7 @@ import { apiGet, apiPatch, apiPost, apiDelete } from "@/api/client";
 import { useToastStore } from "@/stores/toast";
 import TaskLogSection from "@/components/TaskLogSection.vue";
 import { renderMarkdown } from "@/utils/markdown";
+import { Trash2, X } from "lucide-vue-next";
 
 const props = defineProps<{ projectId: number }>();
 
@@ -298,12 +299,12 @@ defineExpose({ reload: loadAll });
           </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">✕</button>
+            <button class="btn-delete-cancel" aria-label="Cancel delete" @click="cancelDeleteTask"><X :size="16" /></button>
           </template>
           <button v-else class="btn-delete-task" title="Delete task" @click="deleteActiveTask">
-            <svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><polyline points="3 6 5 6 21 6"/><path d="M19 6l-1 14a2 2 0 0 1-2 2H8a2 2 0 0 1-2-2L5 6"/><path d="M10 11v6"/><path d="M14 11v6"/><path d="M9 6V4a1 1 0 0 1 1-1h4a1 1 0 0 1 1 1v2"/></svg>
+            <Trash2 :size="16" />
           </button>
-          <button class="btn-close-detail" @click="closeTask" aria-label="Close detail">✕</button>
+          <button class="btn-close-detail" @click="closeTask" aria-label="Close detail"><X :size="16" /></button>
         </div>
 
         <h3 class="detail-title">{{ activeTask.title }}</h3>