feat(design): surface phase PR 3 — Chat surface polish

Per the surface-phase spec for the Chat cluster (ChatView, ChatPanel,
ChatMessage, ChatInputBar, ToolCallCard):

Long-form line-height
- ChatMessage: assistant-bubble .message-content jumps from 1.55 to
  1.7 — chat is a reading surface, not a snippet stream. User
  bubbles stay tighter.
- JournalView: dropped its :deep(.role-assistant .message-content)
  override; ChatMessage handles it now and Journal inherits.

ToolCallCard borders
- Removed the outer 1px border. ToolCallCard always renders inside
  an assistant bubble; the bubble already contains it. Background
  tint differentiates without re-bordering. Per the
  structural-not-decorative rule.
- Error state preserved as a 3px left-edge accent in --color-danger,
  mirroring the assistant bubble's own left-edge pattern.

Button reclassification per Hybrid rule
- ChatView .bulk-link "All"/"None": accent text → --color-text-secondary
  (these are tertiary list-control affordances, not brand moments)
- ChatView .bulk-delete-btn: --color-danger (Error terracotta) →
  --color-action-destructive (Oxblood) per Hybrid; paired with a
  Trash2 icon since destructive should always be reinforced by an
  icon, not just color
- ChatView .btn-delete-conv hover: same Error → Oxblood swap
- .btn-new-conv stays accent (brand moment, correct already)
- .btn-send stays accent gradient (primary brand moment, foundation)

Two-weights-only
- Snapped every font-weight: 600/700 to 500 across ChatView,
  ChatPanel, ChatMessage, ToolCallCard per the doc rule.

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

frontend/src/views/ChatView.vue

@@ -4,7 +4,7 @@ import { useRoute, useRouter } from "vue-router";
 import { useChatStore } from "@/stores/chat";
 import { apiGet } from "@/api/client";
 import ChatPanel from "@/components/ChatPanel.vue";
-import { MoreVertical, Menu, Paperclip } from "lucide-vue-next";
+import { MoreVertical, Menu, Paperclip, Trash2 } from "lucide-vue-next";
 
 const route = useRoute();
 const router = useRouter();
@@ -338,6 +338,7 @@ onUnmounted(() => {
           :disabled="bulkDeleting"
           @click="bulkDelete"
         >
+          <Trash2 :size="16" />
           {{ bulkDeleting ? '...' : bulkConfirm ? `Delete ${selectedIds.size}?` : `Delete (${selectedIds.size})` }}
         </button>
       </div>
@@ -545,22 +546,29 @@ onUnmounted(() => {
 
 .bulk-count { font-size: 0.75rem; color: var(--color-text-muted); flex-shrink: 0; }
 .bulk-link {
-  background: none; border: none; color: var(--color-primary);
+  background: none; border: none; color: var(--color-text-secondary);
   font-size: 0.75rem; cursor: pointer; padding: 0; text-decoration: underline;
 }
+.bulk-link:hover { color: var(--color-text); }
+
+/* Destructive action — Oxblood per Hybrid rule, paired with Trash2 icon */
 .bulk-delete-btn {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.3rem;
   margin-left: auto;
   background: none;
-  border: 1px solid var(--color-danger, #e74c3c);
-  color: var(--color-danger, #e74c3c);
-  border-radius: 4px;
+  border: 1px solid var(--color-action-destructive);
+  color: var(--color-action-destructive);
+  border-radius: var(--radius-sm);
   font-size: 0.75rem;
-  font-weight: 600;
+  font-weight: 500;
   padding: 0.2rem 0.55rem;
   cursor: pointer;
 }
+.bulk-delete-btn:hover:not(:disabled) { background: var(--color-action-destructive); color: #fff; }
 .bulk-delete-btn:disabled { opacity: 0.5; cursor: default; }
-.bulk-delete-btn.confirm { background: var(--color-danger, #e74c3c); color: #fff; }
+.bulk-delete-btn.confirm { background: var(--color-action-destructive-hover); color: #fff; border-color: var(--color-action-destructive-hover); }
 
 .conv-checkbox {
   flex-shrink: 0;
@@ -580,7 +588,7 @@ onUnmounted(() => {
 }
 .conv-group-label {
   font-size: 0.68rem;
-  font-weight: 700;
+  font-weight: 500;
   text-transform: uppercase;
   letter-spacing: 0.06em;
   color: var(--color-text-muted);
@@ -614,7 +622,7 @@ onUnmounted(() => {
   background: none; border: none; color: var(--color-text-muted);
   cursor: pointer; font-size: 1.2rem; padding: 0 0.25rem; line-height: 1;
 }
-.btn-delete-conv:hover { color: var(--color-danger, #e74c3c); }
+.btn-delete-conv:hover { color: var(--color-action-destructive); }
 
 .chat-main {
   flex: 1;
@@ -721,7 +729,7 @@ onUnmounted(() => {
   cursor: pointer;
 }
 .scope-option:hover { background: var(--color-bg-secondary); }
-.scope-option.active { color: var(--color-primary); font-weight: 600; }
+.scope-option.active { color: var(--color-primary); font-weight: 500; }
 
 /* Context toggle button (header) */
 .btn-context-toggle {
@@ -748,7 +756,7 @@ onUnmounted(() => {
 .context-icon { font-size: 0.85rem; line-height: 1; }
 .context-count-badge {
   font-size: 0.65rem;
-  font-weight: 700;
+  font-weight: 500;
   background: var(--color-bg);
   padding: 0.05rem 0.35rem;
   border-radius: 8px;

frontend/src/views/JournalView.vue

@@ -389,12 +389,6 @@ onMounted(async () => {
 
 .journal-chat-panel { flex: 1; min-height: 0; }
 
-/* Long-form reading line-height for journal assistant bubbles
-   (the daily prep is prose, not chat snippets — wants the doc's 1.7) */
-.journal-chat-panel :deep(.role-assistant .message-content) {
-  line-height: 1.7;
-}
-
 /* ── Right column ─────────────────────────────────────────────────────────── */
 .journal-right {
   grid-column: 2;