feat(discussion): add discussion feature for game entities

Create entity_discussion_comments table and API endpoints
Add discussion tabs to Pokemon, Item, Recipe, and Habitat detail views
Support top-level comments, single-level replies, and deletion

frontend/src/views/PokemonDetail.vue

@@ -5,6 +5,7 @@ import { useI18n } from 'vue-i18n';
 import { useRoute } from 'vue-router';
 import DetailSection from '../components/DetailSection.vue';
 import EditHistoryPanel from '../components/EditHistoryPanel.vue';
+import EntityDiscussionPanel from '../components/EntityDiscussionPanel.vue';
 import EntityChips from '../components/EntityChips.vue';
 import PageHeader from '../components/PageHeader.vue';
 import PokemonStatsPanel from '../components/PokemonStatsPanel.vue';
@@ -112,6 +113,7 @@ const skillDropRows = computed(() => pokemon.value?.skills.filter((skill) => ski
 const showEditor = computed(() => route.name === 'pokemon-edit');
 const detailTabs = computed<TabOption[]>(() => [
   { value: 'details', label: t('common.details') },
+  { value: 'discussion', label: t('discussion.title') },
   { value: 'history', label: t('history.editHistory') }
 ]);
 const itemCategoryTabs = computed<TabOption[]>(() => {
@@ -444,6 +446,10 @@ watch(
         </DetailSection>
       </div>
 
+      <div v-else-if="detailTab === 'discussion'" class="detail-tab-panel">
+        <EntityDiscussionPanel entity-type="pokemon" :entity-id="pokemon.id" />
+      </div>
+
       <div v-else class="detail-tab-panel">
         <EditHistoryPanel :entity="pokemon" :history="pokemon.editHistory" />
       </div>