Add OWML mod skeleton and import English translation template

Phase 2 (mod skeleton) + Phase 3 (import English source):

- manifest.json / SlovakTranslation.cs / ILocalizationAPI.cs registering
  "Slovenčina" via xen.LocalizationUtility (Interplanetary Polyglot).
- SlovakTranslation.csproj / .sln building net48 against the OWML and
  OuterWildsGameLibs NuGet packages — no game install needed to compile.
- assets/Translation.xml: English source template (896 KB, 2424 entries,
  keys == values) to be translated into Slovak.
- Project docs (README/PLAN/CLAUDE) and .gitignore.

Build verified: dotnet build -c Release stages a loadable mod folder.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

SlovakTranslation.csproj

@@ -0,0 +1,39 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net48</TargetFramework>
+    <LangVersion>default</LangVersion>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
+    <AppendRuntimeIdentifierToOutputPath>false</AppendRuntimeIdentifierToOutputPath>
+    <CopyLocalLockFileAssemblies>false</CopyLocalLockFileAssemblies>
+    <RootNamespace>SlovakTranslation</RootNamespace>
+    <AssemblyName>SlovakTranslation</AssemblyName>
+  </PropertyGroup>
+
+  <PropertyGroup Condition=" '$(Configuration)' == 'Release' ">
+    <DebugType>none</DebugType>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <!-- Lets net48 build on machines without the .NET Framework targeting pack
+         (e.g. Linux / dotnet SDK only). Build-time only. -->
+    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" PrivateAssets="all" />
+    <PackageReference Include="HarmonyX" Version="2.10.0" />
+    <PackageReference Include="OWML" Version="2.5.2" />
+    <!-- Provides the Outer Wilds / Unity reference DLLs from NuGet, so no game
+         install is needed to compile. -->
+    <PackageReference Include="OuterWildsGameLibs" Version="1.1.12.168" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <None Update="manifest.json">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+    <None Update="default-config.json">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+    <None Update="assets/Translation.xml">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+</Project>