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/index.vue

@@ -96,6 +96,7 @@ onUnmounted(() => {
 const navKind = computed(() => {
     if (route.path === '/') return 'home';
     if (route.path.startsWith('/agent/')) return 'agent';
+    if (route.path === '/resources') return 'resources';
     return null;
 });
 </script>
@@ -123,6 +124,7 @@ const navKind = computed(() => {
                         class="z-25 bg-[var(--bg-base)] relative flex flex-row gap-2 justify-between items-center shrink-0 pb-1.5 h-13 md:h-11 pt-2">
 
                         <SidenavHeader v-if="navKind === 'home'" />
+                        <SidenavHeaderResources v-else-if="navKind === 'resources'" />
                         <SidenavHeaderAgent v-else-if="navKind === 'agent'" />
 
                         <div class="flex items-center justify-end text-[var(--text-secondary)] gap-0.5">
@@ -155,6 +157,7 @@ const navKind = computed(() => {
                     <!-- Main Menu -->
                     <SidenavNavHome v-if="navKind === 'home'" />
                     <SidenavNavAgent v-else-if="navKind === 'agent'" />
+                    <SidenavNavResources v-else-if="navKind === 'resources'" />
                 </div>
 
                 <div class="flex justify-between pt-2 z-25 bg-[var(--bg-base)] pb-2">