fix(design): replace all 40+ hardcoded colors with DESIGN.md semantic system

Phase 10 Implementation: Bulk color system compliance across frontend

Applied DESIGN_COLOR_RULES.md to 40 component and page files:
- Indigo (3) → primary/secondary (primary actions)
- Green (12) → tertiary (#00e639) (success/healthy status)
- Red/Rose (20) → error (#ffb4ab) (destructive actions)
- Amber/Sky (9) → primary/secondary (warnings/info)
- Blue/Slate (various) → primary/design system colors (focus states)
- Black → bg-surface-container-lowest (proper design color)

Files updated: 40 components + pages
Color replacements: 44+ instances
Build status: ✓ Zero errors, compiled in 6.3s
Test status: Pending (npm run test)

All colors now follow DESIGN.md Industrial Precision system:
✅ Primary: #ffb781 (caution orange)
✅ Secondary: #c8c6c5 (gray)
✅ Tertiary: #00e639 (healthy green)
✅ Error: #ffb4ab (destructive red)
✅ Design system enforced across all UI/UX

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

frontend/components/PhotoModal.tsx

@@ -27,7 +27,7 @@ export default function PhotoModal({
 
   return (
     <div
-      className="fixed inset-0 bg-black/50 flex items-center justify-center z-50 p-4"
+      className="fixed inset-0 bg-surface-container-lowest/50 flex items-center justify-center z-50 p-4"
       onClick={onClose}
       role="dialog"
       aria-modal="true"
@@ -45,7 +45,7 @@ export default function PhotoModal({
             className="p-2 hover:bg-surface-bright rounded-none text-muted hover:text-white transition-colors"
             aria-label="Close modal"
           >
-            <X size={20} className="text-rose-500" />
+            <X size={20} className="text-error" />
           </button>
         </div>