feat(dashboard): replace emojis with Font Awesome, add theme support, and styled dialogs

This commit implements three major improvements to the dashboard system:

1. **Font Awesome Icons for Tabs**
   - Replace emoji tab icons (📊, 🌍, 🎒) with Font Awesome classes
   - Update defaultLayout.js with fa-solid icon classes
   - Add automatic migration for existing saved dashboards with emoji icons
   - Implement migrateEmojiIcons() to convert old emoji icons on load
   - Update fallback icons throughout the system

2. **Custom Theme Support for Dashboard**
   - Replace all --SmartTheme* variables with --rpg-* variables
   - Ensure custom themes (sci-fi, fantasy, cyberpunk) apply to dashboard
   - Update CSS for tabs, buttons, dropdowns, modals, and widget cards
   - Dashboard now respects extension themes instead of main SillyTavern theme

3. **Styled Confirmation Dialogs**
   - Create confirmDialog.js with showConfirmDialog() and showAlertDialog()
   - Support three variants: danger (red), warning (yellow), info (blue)
   - Add keyboard navigation (Enter/Escape) and accessibility features
   - Replace all native confirm() and alert() calls with styled dialogs
   - Add confirmation dialog modal to dashboardTemplate.html

Files Modified:
- src/systems/dashboard/confirmDialog.js (NEW)
- src/systems/dashboard/dashboardManager.js
- src/systems/dashboard/defaultLayout.js
- src/systems/dashboard/tabManager.js
- src/systems/dashboard/dashboardIntegration.js
- src/systems/dashboard/editModeManager.js
- src/systems/dashboard/widgets/inventoryWidget.js
- src/systems/dashboard/dashboardTemplate.html
- style.css

src/systems/dashboard/widgets/inventoryWidget.js

@@ -16,6 +16,7 @@
 
 import { parseItems, serializeItems } from '../../../utils/itemParser.js';
 import { sanitizeItemName, sanitizeLocationName } from '../../../utils/security.js';
+import { showAlertDialog } from '../confirmDialog.js';
 
 /**
  * Convert location name to safe HTML ID
@@ -663,7 +664,11 @@ export function registerInventoryWidget(registry, dependencies) {
 
         const itemName = sanitizeItemName(rawItemName);
         if (!itemName) {
-            alert('Invalid item name.');
+            showAlertDialog({
+                title: 'Invalid Item',
+                message: 'Please enter a valid item name.',
+                variant: 'warning'
+            });
             hideAddItemForm(widget, field, location);
             return;
         }
@@ -819,7 +824,11 @@ export function registerInventoryWidget(registry, dependencies) {
 
         const locationName = sanitizeLocationName(rawLocationName);
         if (!locationName) {
-            alert('Invalid location name.');
+            showAlertDialog({
+                title: 'Invalid Location',
+                message: 'Please enter a valid location name.',
+                variant: 'warning'
+            });
             hideAddLocationForm(widget);
             return;
         }
@@ -829,7 +838,11 @@ export function registerInventoryWidget(registry, dependencies) {
 
         // Check if location already exists
         if (inventory.stored[locationName]) {
-            alert('A location with this name already exists.');
+            showAlertDialog({
+                title: 'Duplicate Location',
+                message: 'A location with this name already exists.',
+                variant: 'warning'
+            });
             hideAddLocationForm(widget);
             return;
         }