refactor : migrate UI to Malio layer-ui components (MalioButton, MalioDrawer, MalioSelectCheckbox)

- Replace all AppDrawer with MalioDrawer across 10 drawer components
- Replace native <button> with MalioButton/MalioButtonIcon in all pages and components
- Fix TimeTrackingExportDrawer: use MalioSelectCheckbox for multi-select filters
- Add Malio design system colors (m-btn-*, m-disabled, m-surface) to tailwind.config.ts
- Align toggle button heights with MalioButton (h-[40px])

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/components/admin/AdminBookStackTab.vue

@@ -32,21 +32,19 @@
             </div>
 
             <div class="flex gap-3">
-                <button
-                    type="submit"
-                    class="rounded-md bg-primary-500 px-4 py-2 text-sm font-semibold text-white hover:bg-secondary-500 disabled:opacity-50"
+                <MalioButton
+                    :label="$t('bookstack.settings.save')"
+                    button-class="w-auto px-4"
                     :disabled="isSaving"
-                >
-                    {{ $t('bookstack.settings.save') }}
-                </button>
-                <button
-                    type="button"
-                    class="rounded-md border border-neutral-300 px-4 py-2 text-sm font-semibold text-neutral-700 hover:bg-neutral-50 disabled:opacity-50"
+                    @click="handleSave"
+                />
+                <MalioButton
+                    variant="tertiary"
+                    :label="$t('bookstack.settings.testConnection')"
+                    button-class="w-auto px-4"
                     :disabled="isTesting"
                     @click="handleTest"
-                >
-                    {{ $t('bookstack.settings.testConnection') }}
-                </button>
+                />
             </div>
 
             <p v-if="testResult !== null" class="text-sm font-medium" :class="testResult ? 'text-green-600' : 'text-red-600'">