feat: add resources page with file management

- Add /resources page with file listing, filtering, and bulk operations
- Add useResources composable for file state management
- Add sidenav header and nav components for resources section
- Add files list API endpoint (GET /api/files)
- Track file size during upload
- Add resources link to home navigation

app/components/Sidenav/NavResources.vue

@@ -0,0 +1,33 @@
+<script setup lang="ts">
+import type { ResourceCategory } from '~/composables/useResources';
+
+const { category, setCategory, categoryCount } = await useResources();
+
+const categories: { key: ResourceCategory; label: string; icon: string }[] = [
+    { key: 'all', label: 'All', icon: 'i-mynaui-folder' },
+    { key: 'documents', label: 'Documents', icon: 'i-mynaui-file-text' },
+    { key: 'images', label: 'Images', icon: 'i-mynaui-image' },
+    { key: 'audio', label: 'Audio', icon: 'i-mynaui-music' },
+    { key: 'videos', label: 'Videos', icon: 'i-mynaui-video' },
+];
+</script>
+
+<template>
+    <nav class="flex flex-col gap-1 overflow-auto">
+        <button v-for="cat in categories" :key="cat.key" @click="setCategory(cat.key)"
+            class="flex items-center justify-between gap-2 px-2 h-9 shrink-0 rounded-lg transition-colors w-full"
+            :class="category === cat.key
+                ? 'text-[var(--text-primary)] bg-[var(--color-hover)]'
+                : 'text-[var(--text-secondary)] @hover:bg-[var(--color-hover)]'">
+            <div class="flex items-center gap-2">
+                <div class="h-9 w-9 md:h-7 md:w-7 flex items-center justify-center">
+                    <span class="text-5 md:text-4.5" :class="cat.icon"></span>
+                </div>
+                <span class="md:text-sm font-medium">{{ cat.label }}</span>
+            </div>
+            <span class="text-xs tabular-nums text-[var(--text-tertiary)]">
+                {{ categoryCount(cat.key) }}
+            </span>
+        </button>
+    </nav>
+</template>