Add category management tools to AI chat (list, create, delete)

Three new tools: list_categories shows all categories with type and
parent, create_category adds a new one with optional parent nesting,
delete_category removes non-system categories by name. Frontend renders
category tables, success alerts for creation, and warning alerts for
deletion.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/views/chat/ChatToolResultItem.vue

@@ -120,6 +120,44 @@
       from "{{ data.oldCategory }}" to "{{ data.newCategory }}"
     </v-alert>
   </div>
+
+  <!-- Categories List -->
+  <div v-else-if="type === 'categories' && Array.isArray(data)">
+    <v-table density="compact" class="text-caption rounded-lg mb-2">
+      <thead>
+        <tr>
+          <th>Name</th>
+          <th>Type</th>
+          <th>Parent</th>
+        </tr>
+      </thead>
+      <tbody>
+        <tr v-for="cat in data" :key="cat.id">
+          <td>{{ cat.name }}</td>
+          <td>
+            <v-chip size="x-small" :color="cat.type === 'Income' ? 'success' : cat.type === 'Expense' ? 'error' : 'info'" variant="tonal">
+              {{ cat.type }}
+            </v-chip>
+          </td>
+          <td class="text-medium-emphasis">{{ cat.parentName || '-' }}</td>
+        </tr>
+      </tbody>
+    </v-table>
+  </div>
+
+  <!-- Category Created -->
+  <div v-else-if="type === 'category_created'">
+    <v-alert type="success" variant="tonal" density="compact" class="mb-2 text-caption">
+      Created {{ data.type }} category "{{ data.name }}"{{ data.parentName ? ` under "${data.parentName}"` : '' }}
+    </v-alert>
+  </div>
+
+  <!-- Category Deleted -->
+  <div v-else-if="type === 'category_deleted'">
+    <v-alert type="warning" variant="tonal" density="compact" class="mb-2 text-caption">
+      Deleted {{ data.type }} category "{{ data.name }}"
+    </v-alert>
+  </div>
 </template>
 
 <script setup lang="ts">