feat(design): surface phase PR 7 — edge surfaces polish

Per the spec, the final per-surface PR bundles the smaller / chrome-y /
library-driven views (Header / Home / Calendar / Graph) together with
EventSlideOver since it's the calendar's primary interaction surface.

Button reclassification per Hybrid rule
- CalendarView btn-new-event: accent gradient → Moss action-primary.
  Creating an event is a workflow action, not a brand moment.
- EventSlideOver btn-primary (Save): accent gradient → Moss
- EventSlideOver btn-secondary (Cancel/No): muted ghost → Bronze
  action-secondary
- EventSlideOver btn-danger-ghost (Delete): hardcoded #ef4444 →
  --color-action-destructive ghost (with filled hover)
- EventSlideOver btn-danger (confirm Delete): hardcoded #ef4444 →
  --color-action-destructive filled

Brand-moment CTAs kept on accent
- HomeView btn-workspace-hero: home-page hero CTA into the active
  project — central brand-moment surface, gradient stays
- HomeView btn-workspace-sm: per-card workspace icon with the
  accent-tinted bg + hover-to-accent pattern, kept

Two-weights-only
- Snapped every font-weight 600/700 to 500 across the bundle
  (HomeView, GraphView, CalendarView, AppHeader, EventSlideOver).

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

frontend/src/components/AppHeader.vue

@@ -174,7 +174,7 @@ router.afterEach(() => {
   font-family: 'Fraunces', Georgia, serif;
   font-style: italic;
   font-optical-sizing: auto;
-  font-weight: 600;
+  font-weight: 500;
   font-size: 1rem;
   letter-spacing: -0.01em;
   color: #c4b0f0;
@@ -219,7 +219,7 @@ router.afterEach(() => {
 }
 .nav-link.router-link-active {
   color: var(--color-primary-solid);
-  font-weight: 600;
+  font-weight: 500;
   background: rgba(91, 74, 138, 0.25);
   box-shadow: 0 0 16px rgba(91, 74, 138, 0.3);
 }
@@ -294,7 +294,7 @@ router.afterEach(() => {
 }
 .admin-badge {
   font-size: 0.65rem;
-  font-weight: 700;
+  font-weight: 500;
   text-transform: uppercase;
   letter-spacing: 0.05em;
   color: var(--color-primary);

frontend/src/components/EventSlideOver.vue

@@ -390,7 +390,7 @@ async function doDelete() {
 
 .so-title {
   font-size: 1.05rem;
-  font-weight: 600;
+  font-weight: 500;
   margin: 0;
   color: var(--color-text, #e8e9f0);
 }
@@ -420,7 +420,7 @@ async function doDelete() {
 
 .so-label {
   font-size: 0.78rem;
-  font-weight: 600;
+  font-weight: 500;
   color: var(--color-text-muted, #888);
   text-transform: uppercase;
   letter-spacing: 0.04em;
@@ -492,53 +492,61 @@ async function doDelete() {
   margin-top: auto;
 }
 
+/* Save (in slide-over): Moss action-primary */
 .btn-primary {
-  background: var(--gradient-cta);
+  background: var(--color-action-primary);
   color: #fff;
   border: none;
   border-radius: 8px;
   padding: 0.55rem 1.2rem;
   font-size: 0.9rem;
-  font-weight: 600;
+  font-weight: 500;
   cursor: pointer;
-  transition: opacity 0.15s;
+  transition: background 0.15s;
 }
 .btn-primary:disabled { opacity: 0.5; cursor: not-allowed; }
-.btn-primary:hover:not(:disabled) { opacity: 0.88; }
+.btn-primary:hover:not(:disabled) { background: var(--color-action-primary-hover); }
 
+/* Cancel: Bronze action-secondary */
 .btn-secondary {
-  background: var(--color-input-bg, #111113);
-  border: 1px solid var(--color-border, #2a2b30);
-  color: var(--color-text-muted, #888);
+  background: var(--color-action-secondary);
+  border: none;
+  color: #fff;
   border-radius: 8px;
   padding: 0.55rem 1rem;
   font-size: 0.9rem;
   cursor: pointer;
+  transition: background 0.15s;
 }
-.btn-secondary:hover { background: var(--color-hover, rgba(255,255,255,0.06)); }
+.btn-secondary:hover { background: var(--color-action-secondary-hover); }
 
+/* Delete (entry-point): Oxblood action-destructive ghost */
 .btn-danger-ghost {
   margin-left: auto;
   background: none;
-  border: 1px solid #ef4444;
-  color: #ef4444;
+  border: 1px solid var(--color-action-destructive);
+  color: var(--color-action-destructive);
   border-radius: 8px;
   padding: 0.55rem 1rem;
   font-size: 0.9rem;
   cursor: pointer;
+  transition: background 0.15s, color 0.15s;
 }
-.btn-danger-ghost:hover { background: rgba(239, 68, 68, 0.1); }
+.btn-danger-ghost:hover { background: var(--color-action-destructive); color: #fff; }
 
+/* Confirm-delete: Oxblood filled */
 .btn-danger {
-  background: #ef4444;
+  background: var(--color-action-destructive);
   color: #fff;
   border: none;
   border-radius: 8px;
   padding: 0.55rem 1rem;
   font-size: 0.9rem;
-  font-weight: 600;
+  font-weight: 500;
   cursor: pointer;
+  transition: background 0.15s;
 }
+.btn-danger:hover:not(:disabled) { background: var(--color-action-destructive-hover); }
 .btn-danger:disabled { opacity: 0.5; cursor: not-allowed; }
 
 .delete-confirm-label {