feat: add TagManager and tag filtering (#30 #31)

Issue #30 - TagManager component:
- Create/delete tags with name, category, icon, color
- Color picker with hex input
- Organized display by category
- Integrated in settings page with tabs

Issue #31 - Tag filter for inventory:
- TagFilter component with multi-select
- Filter button in inventory header
- Active filter display with removable badges
- Filters items by selected tags (OR logic)
- Clean "Clear" button

Updates:
- Extended useTags composable with createTag, deleteTag
- Enhanced settings page with tab navigation
- Improved inventory filtering UX

Closes #30, #31

app/pages/index.vue

@@ -21,9 +21,23 @@
         >
           Add Manually
         </UButton>
+
+        <UButton
+          color="gray"
+          size="lg"
+          icon="i-heroicons-funnel"
+          @click="showFilters = !showFilters"
+        >
+          Filter
+        </UButton>
       </div>
     </div>
 
+    <!-- Tag Filters -->
+    <UCard v-if="showFilters" class="mb-6">
+      <TagsTagFilter v-model="selectedTagFilters" />
+    </UCard>
+
     <!-- Add Item Form (Overlay) -->
     <div v-if="showAddForm" class="fixed inset-0 z-50 flex items-start justify-center pt-20 px-4 bg-black/50">
       <div class="w-full max-w-lg">
@@ -46,6 +60,7 @@
     <InventoryList
       ref="inventoryListRef"
       :refresh="refreshKey"
+      :tag-filters="selectedTagFilters"
       @add-item="showAddForm = true"
       @edit-item="editingItem = $event"
     />
@@ -61,10 +76,12 @@ const route = useRoute()
 const router = useRouter()
 
 const showAddForm = ref(false)
+const showFilters = ref(false)
 const editingItem = ref<any>(null)
 const refreshKey = ref(0)
 const inventoryListRef = ref()
 const prefilledData = ref<any>(null)
+const selectedTagFilters = ref<string[]>([])
 
 // Handle scan-to-add flow (Issue #25)
 onMounted(() => {