Fix WinUI getting-started gaps: missing template tip, packaged callout, DLL error FAQ

- start-here.md: add TIP callout if WinUI templates don't appear after VS install
- start-here.md: add NOTE explaining why Packaged template is recommended
- windows-developer-faq.md: add FAQ entry for Microsoft.ui.xaml.dll not found error

Addresses top developer pain points reported in community discussions.

Co-authored-by: Copilot <[email protected]>

Author: GrantMeStrength

hub/apps/get-started/start-here.md

@@ -58,6 +58,9 @@ In the Visual Studio Installer, select the following workloads on the **Workload
 
 * **For C++ app development**, select the **C++ WinUI app development tools** under the **WinUI application development** node in the **Installation details** pane (This will also select any additional required components.)
 
+> [!TIP]
+> If you don't see WinUI templates after installing Visual Studio, open the Visual Studio Installer, select **Modify**, and confirm the **WinUI application development** workload is checked. Restart Visual Studio after modifying the installation.
+
 ---
 
 ## Create and launch your first WinUI app
@@ -66,6 +69,9 @@ In the Visual Studio Installer, select the following workloads on the **Workload
 
 2. Search for **WinUI**, select the **WinUI Blank App (Packaged)** C# project template, and select **Next**.
 
+   > [!NOTE]
+   > The **Packaged** template is recommended for new apps. A packaged app (using MSIX) gives your users a clean install and uninstall experience, and enables Windows features like notifications, background tasks, and the Microsoft Store. You can learn more about the packaged vs. unpackaged choice in [Windows apps: packaging, deployment, and process](intro-pack-dep-proc.md).
+
    :::image type="content" source="images/hello-world/create-project.png" lightbox="images/hello-world/create-project.png" alt-text="Blank, packaged WinUI C# desktop app":::
 
 3. Enter a project name and select **Create**.

hub/apps/get-started/windows-developer-faq.md

@@ -103,6 +103,18 @@ Topics covered include:
 
 </details>
 
+<details><summary>I get a "Unable to load DLL 'Microsoft.ui.xaml.dll'" error when running my app. How do I fix it?</summary>
+
+> This error usually occurs in **unpackaged** app scenarios where the Windows App SDK runtime hasn't been installed on the machine. Try the following:
+>
+> - If you're running a **packaged** app (the recommended default), ensure you're launching via Visual Studio with the **MsixPackage** launch profile selected (not the plain executable profile). The MSIX packaging step installs the required runtime components.
+> - If you're running an **unpackaged** app, you must install the [Windows App SDK runtime](../windows-app-sdk/downloads.md) separately before running the app outside of Visual Studio.
+> - If the error occurs during development, open your `.csproj` and confirm `<WindowsPackageType>MSIX</WindowsPackageType>` is set (for packaged apps), or that you've called `Bootstrap.Initialize()` at startup (for unpackaged apps).
+>
+> See [Deploy apps that use the Windows App SDK](../package-and-deploy/deploy-overview.md) for more details on deployment requirements.
+
+</details>
+
 <details><summary>What is the difference between WinUI and WinUI for UWP?</summary>
 
 > **WinUI** (previously referred to as WinUI 3) is the latest native UI framework for Windows app development. It provides a modern and flexible UI framework for creating visually appealing and interactive Windows apps. WinUI is part of the Windows App SDK and works best with the latest versions of Windows.