feat(webui): Add Models tab and refactor model configuration

- Add standalone Models tab with real-time quota/status display
- Move model identity table from Dashboard to Models tab
- Slim down Dashboard to KPI cards and charts only
- Dashboard charts now use unfiltered data (independent of Models filters)

Settings > Models improvements:
- Remove redundant Alias column (only Mapping is functional)
- Fix column misalignment bug (empty td)
- Add column widths and hidden row opacity styling
- Single row edit constraint (only one Mapping editable at a time)
- showHiddenModels toggle now only affects Settings (not Models tab)
- Update description text to match current functionality

i18n:
- Add 'models' and 'modelsPageDesc' keys (EN/ZH)
- Add 'modelMappingHint' for Claude CLI guidance
- Update 'modelsDesc' to reflect new functionality

public/js/components/dashboard.js

@@ -439,7 +439,7 @@ window.Components.dashboard = () => ({
                         padding: 10,
                         displayColors: true,
                         callbacks: {
-                            label: function(context) {
+                            label: function (context) {
                                 return context.dataset.label + ': ' + context.parsed.y;
                             }
                         }
@@ -531,7 +531,8 @@ window.Components.dashboard = () => ({
             this.charts.quotaDistribution.destroy();
         }
 
-        const rows = Alpine.store('data').quotaRows;
+        // Use UNFILTERED data for global health chart
+        const rows = Alpine.store('data').getUnfilteredQuotaData();
 
         // Dynamic family aggregation (supports any model family)
         const familyStats = {};
@@ -580,12 +581,12 @@ window.Components.dashboard = () => ({
 
             // Labels using translations if possible
             const activeLabel = family === 'claude' ? store.t('claudeActive') :
-                              family === 'gemini' ? store.t('geminiActive') :
-                              `${familyName} ${store.t('activeSuffix')}`;
+                family === 'gemini' ? store.t('geminiActive') :
+                    `${familyName} ${store.t('activeSuffix')}`;
 
             const depletedLabel = family === 'claude' ? store.t('claudeEmpty') :
-                                family === 'gemini' ? store.t('geminiEmpty') :
-                                `${familyName} ${store.t('depleted')}`;
+                family === 'gemini' ? store.t('geminiEmpty') :
+                    `${familyName} ${store.t('depleted')}`;
 
             // Active segment
             data.push(activeVal);