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>

manifest.json

@@ -0,0 +1,11 @@
+{
+  "filename": "SlovakTranslation.dll",
+  "author": "Jaroslav Beneš",
+  "name": "Slovak Localization / Slovenčina",
+  "uniqueName": "Homer.SlovakTranslation",
+  "version": "0.1.0",
+  "owmlVersion": "2.5.2",
+  "dependencies": [
+    "xen.LocalizationUtility"
+  ]
+}