Add reset buttons to color editor modal for individual and bulk color resets

- Add "Reset This Color" button in color preview section for individual resets
- Add "Reset All Colors" button in modal footer for bulk palette reset
- Implement reset callbacks with database persistence via preferences API
- Reorganize color preview layout with flex column for better button placement
- Style reset buttons with appropriate warning colors and hover states
- Support both granular and comprehensive color customization workflows

🤖 Generated with [Claude Code](https://claude.ai/code)

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

frontend/styles.css

@@ -4270,6 +4270,13 @@ body {
     flex-shrink: 0;
 }
 
+.color-preview-info {
+    display: flex;
+    flex-direction: column;
+    gap: var(--spacing-sm);
+    flex: 1;
+}
+
 .color-value {
     font-family: monospace;
     font-size: 0.9rem;
@@ -4277,6 +4284,25 @@ body {
     font-weight: 500;
 }
 
+.reset-this-color-button {
+    background: var(--background-secondary);
+    color: var(--text-secondary);
+    border: 1px solid var(--border-secondary);
+    border-radius: var(--border-radius-small);
+    padding: var(--spacing-xs) var(--spacing-sm);
+    cursor: pointer;
+    font-size: 0.8rem;
+    font-weight: 500;
+    transition: var(--transition-fast);
+    align-self: flex-start;
+}
+
+.reset-this-color-button:hover {
+    background: var(--background-tertiary);
+    color: var(--text-primary);
+    border-color: var(--text-primary);
+}
+
 .color-input-section {
     margin-bottom: var(--spacing-lg);
 }
@@ -4359,7 +4385,7 @@ body {
     border-radius: 0 0 var(--border-radius-medium) var(--border-radius-medium);
 }
 
-.cancel-button, .save-button {
+.cancel-button, .reset-all-button, .save-button {
     padding: var(--spacing-sm) var(--spacing-md);
     border: 1px solid var(--border-secondary);
     border-radius: var(--border-radius-small);
@@ -4379,6 +4405,19 @@ body {
     color: var(--text-primary);
 }
 
+.reset-all-button {
+    background: var(--warning-color);
+    color: white;
+    border-color: var(--warning-color);
+    margin-left: auto;
+    margin-right: var(--spacing-sm);
+}
+
+.reset-all-button:hover {
+    background: #e0a800;
+    border-color: #e0a800;
+}
+
 .save-button {
     background: var(--info-color);
     color: white;