feat: Add loot builder frontend — Pinia store, views, 4 components, router + nav

Implements the complete frontend for BetterLoot profile management:
- Pinia store (loot.ts) with CRUD, import/export, apply-to-server actions
- LootBuilderView orchestrator with profile bar, modals, two-column layout
- LootContainerSidebar with categorized container list, search, config indicators
- LootItemEditor for per-container item settings and ungrouped item table
- LootItemPicker modal with searchable/filterable Rust item grid
- LootGroupEditor for reusable loot group management
- Router integration at /loot-builder
- Sidebar nav item with Crosshair icon and loot.view permission

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

frontend/src/components/loot/LootItemPicker.vue

@@ -0,0 +1,88 @@
+<script setup lang="ts">
+import { ref, computed } from 'vue'
+import { rustItems, itemCategories } from '@/data/rust-items'
+import { Search, X } from 'lucide-vue-next'
+
+const emit = defineEmits<{
+  select: [shortname: string]
+  close: []
+}>()
+
+const searchQuery = ref('')
+const selectedCategory = ref<string>('all')
+
+const filteredItems = computed(() => {
+  let items = rustItems
+  if (selectedCategory.value !== 'all') {
+    items = items.filter(i => i.category === selectedCategory.value)
+  }
+  const q = searchQuery.value.toLowerCase()
+  if (q) {
+    items = items.filter(i => i.name.toLowerCase().includes(q) || i.shortname.toLowerCase().includes(q))
+  }
+  return items
+})
+</script>
+
+<template>
+  <div class="fixed inset-0 bg-black/60 z-50 flex items-center justify-center p-4" @click.self="emit('close')">
+    <div class="bg-neutral-900 border border-neutral-800 rounded-xl w-full max-w-2xl max-h-[80vh] flex flex-col">
+      <!-- Header -->
+      <div class="p-4 border-b border-neutral-800 flex items-center justify-between">
+        <h2 class="text-lg font-semibold text-neutral-100">Add Item</h2>
+        <button @click="emit('close')" class="text-neutral-500 hover:text-neutral-300">
+          <X class="w-5 h-5" />
+        </button>
+      </div>
+
+      <!-- Search + Filter -->
+      <div class="p-4 space-y-3 border-b border-neutral-800">
+        <div class="relative">
+          <Search class="absolute left-3 top-1/2 -translate-y-1/2 w-4 h-4 text-neutral-500" />
+          <input
+            v-model="searchQuery"
+            placeholder="Search items..."
+            class="w-full bg-neutral-800 border border-neutral-700 rounded-lg pl-9 pr-3 py-2 text-sm text-neutral-200"
+            autofocus
+          />
+        </div>
+        <div class="flex flex-wrap gap-1">
+          <button
+            @click="selectedCategory = 'all'"
+            class="px-2 py-1 rounded text-xs"
+            :class="selectedCategory === 'all' ? 'bg-oxide-500 text-white' : 'bg-neutral-800 text-neutral-400 hover:text-neutral-200'"
+          >
+            All
+          </button>
+          <button
+            v-for="cat in itemCategories"
+            :key="cat"
+            @click="selectedCategory = cat"
+            class="px-2 py-1 rounded text-xs capitalize"
+            :class="selectedCategory === cat ? 'bg-oxide-500 text-white' : 'bg-neutral-800 text-neutral-400 hover:text-neutral-200'"
+          >
+            {{ cat }}
+          </button>
+        </div>
+      </div>
+
+      <!-- Item Grid -->
+      <div class="flex-1 overflow-y-auto p-4">
+        <div class="grid grid-cols-2 sm:grid-cols-3 gap-2">
+          <button
+            v-for="item in filteredItems"
+            :key="item.shortname"
+            @click="emit('select', item.shortname)"
+            class="text-left px-3 py-2 bg-neutral-800 rounded-lg hover:bg-neutral-700 transition-colors group"
+          >
+            <div class="text-sm text-neutral-200 group-hover:text-oxide-400">{{ item.name }}</div>
+            <div class="text-xs text-neutral-500">{{ item.shortname }}</div>
+          </button>
+        </div>
+        <div v-if="filteredItems.length === 0" class="text-center py-8 text-neutral-500">
+          No items found
+        </div>
+      </div>
+    </div>
+  </div>
+</template>