client: reorganize files, router and add inventory skeleton

website/client/components/inventory/index.vue

@@ -0,0 +1,19 @@
+<template lang="pug">
+.row
+  .sixteen.wide.column
+    .ui.secondary.menu
+      router-link.item(:to="{name: 'inventory'}")
+        span(v-once) {{ $t('inventory') }}
+      router-link.item(:to="{name: 'equipment'}")
+        span(v-once) {{ $t('equipment') }}
+      router-link.item(:to="{name: 'stable'}")
+        span(v-once) {{ $t('stable') }}
+
+  .sixteen.wide.column
+    router-view
+</template>
+
+<script>
+export default {
+};
+</script>