Adds update checker with user preference

Introduces an update checker feature that respects the user's preference, allowing them to enable or disable automatic update checks.

The setting is persisted in the config file and synced to the backend.

Also introduces a page dedicated to listing music that inspired the project, and makes some minor UI improvements

frontend/src/lib/components/SidebarApp.svelte

@@ -3,7 +3,7 @@
   import * as Sidebar from "$lib/components/ui/sidebar/index.js";
   import { dangerZoneEnabled } from "$lib/stores/app";
   import * as m from "$lib/paraglide/messages.js";
-  import { Mail, Heart } from "@lucide/svelte/icons";
+  import { Mail, Heart, Info } from "@lucide/svelte/icons";
 
   const CLICK_WINDOW_MS = 4000;
   const REQUIRED_CLICKS = 10;
@@ -46,7 +46,7 @@
     {
       title: m.sidebar_credits(),
       url: "/credits",
-      icon: Heart,
+      icon: Info,
       disabled: false,
       id: 3,
     },

frontend/src/lib/stores/settings.svelte.ts

@@ -11,6 +11,7 @@ const defaults: EMLy_GUI_Settings = {
     previewFileSupportedTypes: ["jpg", "jpeg", "png"],
     enableAttachedDebuggerProtection: true,
     useDarkEmailViewer: true,
+    enableUpdateChecker: true,
 };
 
 class SettingsStore {

frontend/src/lib/types.d.ts

@@ -9,6 +9,25 @@ interface EMLy_GUI_Settings {
     previewFileSupportedTypes?: SupportedFileTypePreview[];
     enableAttachedDebuggerProtection?: boolean;
     useDarkEmailViewer?: boolean;
+    enableUpdateChecker?: boolean;
 }
 
 type SupportedLanguages = "en" | "it";
+// Plugin System Types
+interface PluginFormatSupport {
+    extensions: string[];
+    mime_types?: string[];
+    priority: number;
+}
+
+interface PluginInfo {
+    name: string;
+    version: string;
+    author: string;
+    description: string;
+    capabilities: string[];
+    status: "unloaded" | "loading" | "active" | "error" | "disabled";
+    enabled: boolean;
+    last_error?: string;
+    supported_formats?: PluginFormatSupport[];
+}