feat: enhance habitat appearances and item relations

Replace item tags with favorite things to unify entity tagging
Allow multiple maps, times, and weathers per habitat appearance
Make item usage optional and translate API error messages to Chinese
Add .dockerignore files for backend and frontend

frontend/src/views/PokemonDetail.vue

@@ -37,7 +37,7 @@ onMounted(async () => {
       <section class="detail-section">
         <h2>栖息地</h2>
         <ul class="row-list">
-          <li v-for="habitat in pokemon.habitats" :key="`${habitat.id}-${habitat.map.id}-${habitat.time_of_day}`">
+          <li v-for="habitat in pokemon.habitats" :key="`${habitat.id}-${habitat.map.id}-${habitat.time_of_day}-${habitat.weather}`">
             <RouterLink :to="`/habitats/${habitat.id}`">{{ habitat.name }}</RouterLink>
             <span>{{ habitat.time_of_day }} · {{ habitat.weather }} · {{ habitat.rarity }} 星 · {{ habitat.map.name }}</span>
           </li>