Auto-install .NET 8 runtimes if missing

A fresh Windows Server install has neither ASP.NET Core 8 nor .NET
Desktop 8, so the Service refuses to start and the GUI fails to
launch — the symptoms link to aka.ms/dotnet-core-applaunch but it's
not obvious from the GUI itself what's wrong.

Setup now:
- Detects each runtime by looking for an 8.x folder under
  %ProgramFiles%\dotnet\shared\Microsoft.{AspNetCore,WindowsDesktop}.App
- Uses Inno Setup's built-in TDownloadWizardPage to fetch any missing
  runtime from the aka.ms redirect and runs `/install /quiet /norestart`
- Treats Microsoft's 1638 / 3010 / 1641 exit codes as success

If the box has no internet, the prereq install fails with a clear
message and a "continue anyway?" prompt. README + installation docs
list the manual download URLs and `dotnet --list-runtimes` check;
troubleshooting has a section pointing at the same fix when the
service won't start after install.

Directory.Build.props

@@ -1,7 +1,7 @@
 <Project>
 
   <PropertyGroup>
-    <Version>0.1.5</Version>
+    <Version>0.1.4</Version>
     <Authors>Justin Paul</Authors>
     <Company>Justin Paul</Company>
     <Product>Webhook Server</Product>