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/dashboardTemplate.html

@@ -132,4 +132,28 @@
             </div>
         </div>
     </div>
+
+    <!-- Confirmation Dialog Modal -->
+    <div id="rpg-confirm-dialog" class="rpg-modal rpg-confirm-modal" style="display: none;">
+        <div class="rpg-modal-content rpg-confirm-content">
+            <div class="rpg-modal-header rpg-confirm-header">
+                <div class="rpg-confirm-header-content">
+                    <i id="rpg-confirm-icon" class="rpg-confirm-icon"></i>
+                    <h3 id="rpg-confirm-title"></h3>
+                </div>
+                <button class="rpg-modal-close rpg-confirm-close">
+                    <i class="fa-solid fa-times"></i>
+                </button>
+            </div>
+
+            <div class="rpg-modal-body rpg-confirm-body">
+                <p id="rpg-confirm-message"></p>
+            </div>
+
+            <div class="rpg-modal-footer rpg-confirm-footer">
+                <button class="rpg-btn-secondary" id="rpg-confirm-cancel"></button>
+                <button class="rpg-btn-primary" id="rpg-confirm-confirm"></button>
+            </div>
+        </div>
+    </div>
 </div>