feat(election): candidate lock UI, director board grouping, collapsible elections, and member photos

- Candidate board: lock Remove and Change Symbol buttons when voting is active (VOTING_OPEN/CLOSED/RESULT_DECLARED/CANCELLED)
- Director board: group directors by election with Current/Past badges, sorted newest first
- Past election groups collapsed by default; click header to expand/collapse with chevron animation
- Show first 6 directors, expand button for remaining members
- Load member photos in director cards via clientImage API (fallback to initials)
- 4-column responsive grid for director cards

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/election/components/candidate-board/candidate-board.component.scss

@@ -375,6 +375,31 @@
     border-radius: 6px;
     font-size: 11px;
   }
+
+  .locked-badge {
+    display: inline-flex;
+    align-items: center;
+    gap: 3px;
+    background: #fffbeb;
+    color: #92400e;
+    border: 1px solid #fde68a;
+    padding: 4px 10px;
+    border-radius: 6px;
+    font-size: 11px;
+    font-weight: 600;
+
+    mat-icon {
+      font-size: 12px;
+      height: 12px;
+      width: 12px;
+    }
+  }
+}
+
+.btn-locked {
+  opacity: 0.5;
+  pointer-events: none;
+  cursor: not-allowed !important;
 }
 
 // ── Candidate Detail Drawer ────────────────────────────────────
@@ -734,6 +759,28 @@
   }
 }
 
+.locked-notice {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  width: 100%;
+  margin-top: 8px;
+  padding: 10px 14px;
+  background: #fffbeb;
+  color: #92400e;
+  border: 1px solid #fde68a;
+  border-radius: 8px;
+  font-size: 13px;
+  font-weight: 500;
+
+  mat-icon {
+    font-size: 16px;
+    height: 16px;
+    width: 16px;
+    flex-shrink: 0;
+  }
+}
+
 .btn-remove-full {
   display: flex;
   align-items: center;