04-05: Reset to Original feature - custom workouts can be reverted to program versions

- Added reset button (refresh icon) to custom workout cards
- Implemented confirmation dialog to prevent accidental resets
- Integrated with DELETE /api/custom-workouts/:id endpoint
- Added CSS styling: reset button, success message, modal dialog
- Added refresh icon to SVG library
- Frontend build successful

Changes:
- frontend/src/pages/WorkoutSelectPage.jsx (reset flow logic)
- frontend/src/App.css (170 new lines for reset/modal styling)
- frontend/src/components/Icons.jsx (refresh icon)
- Checkpoint updated with task completion metadata

frontend/src/App.css

@@ -2998,3 +2998,173 @@
 .workout-select-card:hover .workout-badge {
   box-shadow: 0 2px 6px rgba(0, 0, 0, 0.25);
 }
+
+/* Reset button for custom workouts */
+.reset-btn {
+  position: absolute;
+  top: -8px;
+  right: -8px;
+  width: 32px;
+  height: 32px;
+  border-radius: var(--radius-full);
+  background: var(--accent);
+  border: 2px solid var(--bg-primary);
+  color: white;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  cursor: pointer;
+  transition: all 0.2s ease;
+  box-shadow: 0 2px 8px rgba(255, 107, 74, 0.3);
+  padding: 0;
+  min-width: 32px;
+  min-height: 32px;
+}
+
+.reset-btn:hover {
+  background: #e85a3c;
+  transform: scale(1.1);
+  box-shadow: 0 4px 12px rgba(255, 107, 74, 0.4);
+}
+
+.reset-btn:active {
+  transform: scale(0.95);
+}
+
+/* Success message */
+.success-message {
+  display: flex;
+  align-items: center;
+  gap: var(--space-2);
+  padding: var(--space-3) var(--space-4);
+  background: linear-gradient(135deg, var(--success), #16a34a);
+  color: white;
+  border-radius: var(--radius-lg);
+  margin-bottom: var(--space-4);
+  animation: slideDown 0.3s ease;
+  box-shadow: 0 4px 12px rgba(34, 197, 94, 0.2);
+}
+
+@keyframes slideDown {
+  from {
+    opacity: 0;
+    transform: translateY(-10px);
+  }
+  to {
+    opacity: 1;
+    transform: translateY(0);
+  }
+}
+
+/* Modal dialog styles */
+.modal-overlay {
+  position: fixed;
+  top: 0;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  background: rgba(0, 0, 0, 0.5);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  z-index: 1000;
+  animation: fadeIn 0.2s ease;
+}
+
+@keyframes fadeIn {
+  from { opacity: 0; }
+  to { opacity: 1; }
+}
+
+.modal-dialog {
+  background: var(--bg-primary);
+  border-radius: var(--radius-xl);
+  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3);
+  max-width: 400px;
+  width: 90%;
+  animation: slideUp 0.3s ease;
+  overflow: hidden;
+}
+
+@keyframes slideUp {
+  from {
+    opacity: 0;
+    transform: translateY(20px);
+  }
+  to {
+    opacity: 1;
+    transform: translateY(0);
+  }
+}
+
+.modal-header {
+  padding: var(--space-4);
+  border-bottom: 1px solid var(--border);
+}
+
+.modal-header h2 {
+  font-size: var(--font-lg);
+  font-weight: 700;
+  margin: 0;
+  color: var(--text-primary);
+}
+
+.modal-body {
+  padding: var(--space-4);
+}
+
+.modal-body p {
+  font-size: var(--font-md);
+  color: var(--text-secondary);
+  line-height: 1.5;
+  margin: 0;
+}
+
+.modal-footer {
+  padding: var(--space-4);
+  border-top: 1px solid var(--border);
+  display: flex;
+  gap: var(--space-2);
+  justify-content: flex-end;
+}
+
+.modal-btn {
+  padding: var(--space-2) var(--space-4);
+  border-radius: var(--radius-md);
+  border: none;
+  cursor: pointer;
+  font-size: var(--font-md);
+  font-weight: 600;
+  transition: all 0.2s ease;
+  min-height: 40px;
+}
+
+.modal-btn:disabled {
+  opacity: 0.6;
+  cursor: not-allowed;
+}
+
+.modal-btn.cancel {
+  background: var(--bg-secondary);
+  color: var(--text-primary);
+  border: 1px solid var(--border);
+}
+
+.modal-btn.cancel:hover:not(:disabled) {
+  background: var(--bg-tertiary);
+  border-color: var(--border);
+}
+
+.modal-btn.confirm {
+  background: var(--accent);
+  color: white;
+}
+
+.modal-btn.confirm:hover:not(:disabled) {
+  background: #e85a3c;
+  box-shadow: 0 4px 12px rgba(255, 107, 74, 0.3);
+}
+
+.modal-btn.confirm:active:not(:disabled) {
+  transform: scale(0.98);
+}