launcher: v0.1 — PhotinoNET shell + multi-version orchestration

Single-download .NET 9 self-contained launcher for hosting / joining
DorkNet servers. Reads versions.json from main to discover supported
client builds, fetches the matching server binary + client patcher
from GitHub Releases per branch, manages the server subprocess +
Cloudflare quick-tunnel, and wraps it all in a PhotinoNET window.

Code layout:
- Program.cs           PhotinoNET window + message bridge bootstrap
- Backend/             AppPaths, AppState, VersionsManifest,
                       ReleaseDownloader, ServerProcess, ClientPatcher,
                       Tunnel, RecRoomPicker, JoinCode, MessageBridge
- ui/                  index.html + style.css + app.js (no build step)
- RELEASES.md          GitHub Releases artifact contract per-version
                       branches must publish to

Per-version branches need to ship two release assets per tag:
- dorknet-server-{version_key}-win-x64.zip
- dorknet-clientpatch-{version_key}.zip
(see launcher/RELEASES.md for the full naming + arg contract)

Photon AppIds, JWT secret, and the picked Rec Room path stay
per-machine; the launcher never bundles them.

launcher/DorkNet.Launcher.csproj

@@ -0,0 +1,35 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>WinExe</OutputType>
+    <TargetFramework>net9.0-windows</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <UseWindowsForms>true</UseWindowsForms>
+    <RootNamespace>DorkNet.Launcher</RootNamespace>
+    <AssemblyName>dorknet</AssemblyName>
+    <ApplicationManifest>app.manifest</ApplicationManifest>
+    <PublishSingleFile>true</PublishSingleFile>
+    <SelfContained>true</SelfContained>
+    <RuntimeIdentifier>win-x64</RuntimeIdentifier>
+    <IncludeNativeLibrariesForSelfExtract>true</IncludeNativeLibrariesForSelfExtract>
+    <EnableCompressionInSingleFile>true</EnableCompressionInSingleFile>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <!-- PhotinoNET wraps WebView2 with a tiny .NET host. The WebView2 runtime
+         ships in Windows 11 + modern Windows 10 (Edge auto-installs it). -->
+    <PackageReference Include="Photino.NET" Version="4.0.16" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <!-- UI assets get copied next to the binary at publish time so the
+         PhotinoNET window can load them from disk. Keeps the binary
+         smaller than embedding base64; the user can also patch the UI
+         in-place without rebuilding the .exe. -->
+    <None Update="ui\**\*">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
+</Project>