Add Install Scripts (winget .NET 10 install) for the no-runtime case (held for next release)

RemSound is a .NET 10 app, so it can't install its own runtime — it can't start without it. A
plain .cmd/.ps1 (which run on what's already in Windows) sidesteps that: double-click
"Install Scripts\Install .NET for RemSound.cmd" and it winget-installs the .NET 10 Desktop Runtime
(Microsoft.DotNet.DesktopRuntime.10), falling back to opening Microsoft's download page if winget
is absent. Modelled on Andre Louis's accessible-sensor-readout Install_Scripts (his install .NET
Framework 4.8 because SR is Framework; ours installs the .NET 10 Desktop Runtime RemSound needs).

Bundled into the build + release zip via csproj Content + EnsureInstallScriptsPublished target.
Manual Quick-start note points users here if RemSound won't start. Held for the next release.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

readme.html

@@ -74,6 +74,10 @@ ul, ol { padding-left: 1.4em; }
 
 <h2 id="quick-start">2. Quick start</h2>
 
+<div class="note">
+<strong>If RemSound won't start</strong> &mdash; if Windows says it needs &ldquo;.NET&rdquo; &mdash; RemSound runs on the <strong>Microsoft .NET 10 Desktop Runtime</strong>. Most up-to-date Windows machines already have it; if yours doesn't, open the <strong>Install Scripts</strong> folder sitting next to <code>RemSound.exe</code> and double-click <strong>Install .NET for RemSound.cmd</strong>. It fetches and installs it for you (using winget, the Windows package manager), and then RemSound will start. There's a <code>.ps1</code> version in the same folder for PowerShell users. If you'd rather do it by hand, the script opens Microsoft's download page, where you pick &ldquo;.NET Desktop Runtime&rdquo; for &ldquo;x64&rdquo;.
+</div>
+
 <p>Let's assume you and a friend both have RemSound running, and that your two computers can reach each other on the network (the same Wi-Fi, the same Tailscale account, and so on).</p>
 
 <ol>