feat(frontend): layout header + drawer + router (9 routes)

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

frontend/src/stores/gardens.js

@@ -0,0 +1,22 @@
+import { defineStore } from 'pinia';
+import { ref } from 'vue';
+import { gardensApi } from '@/api/gardens';
+export const useGardensStore = defineStore('gardens', () => {
+    const gardens = ref([]);
+    const loading = ref(false);
+    async function fetchAll() {
+        loading.value = true;
+        gardens.value = await gardensApi.list();
+        loading.value = false;
+    }
+    async function create(g) {
+        const created = await gardensApi.create(g);
+        gardens.value.push(created);
+        return created;
+    }
+    async function remove(id) {
+        await gardensApi.delete(id);
+        gardens.value = gardens.value.filter(g => g.id !== id);
+    }
+    return { gardens, loading, fetchAll, create, remove };
+});