Improve magnet handler registration

- Removed HTTPS protocol check in `registerMagnetHandler()`. Now using `this.canRegisterMagnetHandler = !!(window.isSecureContext && 'registerProtocolHandler' in navigator);` to determine support for protocol handler registration in a secure context.
- Updated the registration button and help text to respond dynamically based on `canRegisterMagnetHandler` and provide better user experience and messaging when unsupported.
- Wrapped `navigator.registerProtocolHandler()` in a try catch block to handle registration failures gracefully and avoid unhandled exceptions.

client/src/app/navbar/navbar.component.html

@@ -37,7 +37,7 @@
           <i class="fas fa-cog" aria-hidden="true"></i>
         </span>
         <span>Settings</span>
-      </a>    
+      </a>
       <a class="navbar-item" *ngIf="profile" href="{{ providerLink }}" target="_blank" rel="noopener">
         <span class="icon">
           <i class="fas fa-euro-sign" aria-hidden="true"></i>

client/src/app/settings/settings.component.html

@@ -142,13 +142,25 @@
 </div>
 
 <div class="field" *ngIf="activeTab === 0">
-  <label class="label">Allow client to handle magnet links</label>
-    <div class="control">
-      <button class="button is-info" type="button" (click)="registerMagnetHandler()">
-        <span>Register Handler</span>
-      </button>
-    </div>
-    <p class="help">This will register the client as your browser's default handler for magnet links. Clicking a magnet link will automatically open it in the new torrent screen for downloading.</p>
+  <label class="label">Register client as magnet link handler</label>
+  <div class="control">
+    <button 
+      class="button is-info" 
+      type="button" 
+      (click)="registerMagnetHandler()" 
+      [disabled]="!canRegisterMagnetHandler">
+      <span>
+        {{ canRegisterMagnetHandler ? 'Register Handler' : 'Unavailable in This Browser' }}
+      </span>
+    </button>
+  </div>
+  <p class="help">
+    {{
+      canRegisterMagnetHandler
+        ? "This will attempt to register the client as your browser's default handler for magnet links and automatically open them in the new torrent screen for downloading."
+        : "Magnet link registration is unavailable because either your browser does not support it or the client is not being served to you in a secure context."
+    }}
+  </p>
 </div>
 
 <div class="field" *ngIf="activeTab < 99">

client/src/app/settings/settings.component.ts

@@ -28,10 +28,13 @@ export class SettingsComponent implements OnInit {
   public testAria2cConnectionError: string = null;
   public testAria2cConnectionSuccess: string = null;
 
+  public canRegisterMagnetHandler = false;
+
   constructor(private settingsService: SettingsService) {}
 
   ngOnInit(): void {
     this.reset();
+    this.canRegisterMagnetHandler = !!(window.isSecureContext && 'registerProtocolHandler' in navigator);
   }
 
   public reset(): void {
@@ -139,20 +142,13 @@ export class SettingsComponent implements OnInit {
       },
     );
   }
-  
+
   public registerMagnetHandler(): void {
-    if (window.location.protocol !== "https:") {
-      alert("Magnet link handler registration requires a secure connection. Please ensure the client is being served over HTTPS to enable this feature.");
-      return;
-    }
-
-    const handlerUrl = `${window.location.origin}/add?magnet=%s`;
-
-    if (navigator.registerProtocolHandler) {
-      navigator.registerProtocolHandler("magnet", handlerUrl);
-      alert("Your browser will display a prompt asking if you'd like to add the client as the default application for magnet links. Please confirm to complete the setup.");
-    } else {
-      alert("Magnet link registration failed. Your browser does not support registering custom protocol handlers.");
+    try {
+      navigator.registerProtocolHandler("magnet", `${window.location.origin}/add?magnet=%s`);
+      alert("Success! Your browser will now prompt you to confirm and add the client as the default handler for magnet links.");
+    } catch (error) {
+      alert("Magnet link registration failed.");
     }
   }
 }