feat(design): surface phase PR 5 — Project + Workspace polish

Per the surface-phase spec for the Project list, Project view, and
3-panel Workspace cluster:

Button reclassification per Hybrid rule
- ProjectView:
  - btn-workspace ("Open Workspace"): kept on accent gradient — the
    workspace is the project's central feature moment, a Scribe-
    flavored action, brand moment per the doc.
  - btn-share: muted-outline → Bronze action-secondary
  - btn-danger-outline (Delete project): generic-border + danger-on-
    hover → Oxblood outline + filled hover (proper destructive)
  - btn-save-panel: accent gradient → Moss action-primary
  - btn-ms-confirm (milestone confirm): flat accent → Moss
  - btn-ms-cancel: ghost → Bronze action-secondary
  - .modal-btn-danger: --color-danger → --color-action-destructive
- ProjectListView:
  - btn-primary ("+ New Project"): flat accent → Moss action-primary.
    Empty-state CTA (.empty-action) keeps accent — that *is* a
    brand moment per Hybrid, "create your first project".
- WorkspaceTaskPanel + WorkspaceNoteEditor:
  - btn-delete-task / btn-delete: hover --color-danger → Oxblood
  - btn-delete-confirm / btn-confirm-delete: --color-danger pair →
    --color-action-destructive pair, with filled hover for stronger
    affordance
  - btn-save (WorkspaceNoteEditor): flat accent → Moss
- WorkspaceChatWidget:
  - History toggle: replaced unicode ▾ with Lucide ChevronDown
    (PR 1 carry-over for emoji-as-icon)

Two-weights-only
- Snapped every font-weight 600/700 to 500 across the cluster.

Borders kept (per structural-not-decorative rule)
- Milestone group cards: standalone containers, keep
- Project cards in list: standalone containers, keep
- Task slide-over panel: drawer modal, keep
- Workspace 3-panel separators: major section dividers, keep

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

frontend/src/views/ProjectListView.vue

@@ -283,18 +283,21 @@ function overallPct(project: Project): { total: number; pct: number } {
   margin: 0;
 }
 
+/* Moss action-primary per Hybrid — list-view utility action,
+   not a brand moment. Empty-state .empty-action below keeps accent. */
 .btn-primary {
   padding: 0.45rem 1rem;
-  background: var(--color-primary);
+  background: var(--color-action-primary);
   color: #fff;
   border: none;
   border-radius: var(--radius-sm);
   cursor: pointer;
   font-size: 0.9rem;
   font-family: inherit;
+  transition: background 0.15s;
 }
 .btn-primary:hover {
-  opacity: 0.9;
+  background: var(--color-action-primary-hover);
 }
 
 .filter-tabs {
@@ -321,7 +324,7 @@ function overallPct(project: Project): { total: number; pct: number } {
 .tab-btn.active {
   color: var(--color-primary);
   border-bottom-color: var(--color-primary);
-  font-weight: 600;
+  font-weight: 500;
 }
 
 .loading-msg,
@@ -336,7 +339,7 @@ function overallPct(project: Project): { total: number; pct: number } {
 
 .empty-state-rich { text-align: center; padding: 3rem 1rem; color: var(--color-text-muted); }
 .empty-icon { font-size: 2.5rem; margin-bottom: 0.75rem; opacity: 0.3; }
-.empty-title { font-size: 1rem; font-weight: 600; color: var(--color-text-secondary); margin: 0 0 0.35rem; }
+.empty-title { font-size: 1rem; font-weight: 500; color: var(--color-text-secondary); margin: 0 0 0.35rem; }
 .empty-sub { font-size: 0.85rem; margin: 0 0 1rem; }
 .empty-action { display: inline-block; padding: 0.4rem 1rem; border: 1px solid var(--color-primary); border-radius: var(--radius-sm); color: var(--color-primary); background: none; cursor: pointer; font-size: 0.85rem; transition: background 0.15s, color 0.15s; }
 .empty-action:hover { background: var(--color-primary); color: #fff; }
@@ -389,7 +392,7 @@ function overallPct(project: Project): { total: number; pct: number } {
 }
 .project-title {
   font-size: 1rem;
-  font-weight: 600;
+  font-weight: 500;
   color: var(--color-text);
   min-width: 0;
   flex: 1;
@@ -398,7 +401,7 @@ function overallPct(project: Project): { total: number; pct: number } {
 
 .status-badge {
   font-size: 0.7rem;
-  font-weight: 700;
+  font-weight: 500;
   text-transform: uppercase;
   letter-spacing: 0.04em;
   padding: 0.15rem 0.45rem;
@@ -426,7 +429,7 @@ function overallPct(project: Project): { total: number; pct: number } {
   line-height: 1.4;
 }
 .field-label {
-  font-weight: 600;
+  font-weight: 500;
   color: var(--color-text-secondary);
 }
 
@@ -462,7 +465,7 @@ function overallPct(project: Project): { total: number; pct: number } {
   flex-shrink: 0;
   min-width: 2.5rem;
   text-align: right;
-  font-weight: 600;
+  font-weight: 500;
 }
 
 .milestone-bars {
@@ -545,7 +548,7 @@ function overallPct(project: Project): { total: number; pct: number } {
 }
 .modal-field label {
   font-size: 0.875rem;
-  font-weight: 600;
+  font-weight: 500;
   color: var(--color-text);
 }
 .required {