chore: add GitHub Actions workflow for building mod package

.github/workflows/build.yml

@@ -0,0 +1,80 @@
+name: Build Mod Package
+
+on:
+  push:
+    branches:
+      - main
+      - master
+    tags:
+      - "v*"
+  pull_request:
+  workflow_dispatch:
+  release:
+    types:
+      - published
+
+permissions:
+  contents: write
+
+jobs:
+  build:
+    runs-on: windows-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup .NET 8
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: "8.0.x"
+
+      - name: Download latest LSLib release
+        shell: pwsh
+        run: |
+          $ErrorActionPreference = "Stop"
+          $release = Invoke-RestMethod -Uri "https://api.github.com/repos/Norbyte/lslib/releases/latest"
+          $asset = $release.assets | Where-Object { $_.name -match '\.zip$' } | Select-Object -First 1
+
+          if (-not $asset) {
+              throw "Could not find a downloadable LSLib zip asset in the latest release."
+          }
+
+          New-Item -ItemType Directory -Path ".tools/lslib" -Force | Out-Null
+          Invoke-WebRequest -Uri $asset.browser_download_url -OutFile ".tools/lslib/lslib.zip"
+          Expand-Archive -LiteralPath ".tools/lslib/lslib.zip" -DestinationPath ".tools/lslib" -Force
+
+      - name: Resolve Divine executable
+        id: divine
+        shell: pwsh
+        run: |
+          $ErrorActionPreference = "Stop"
+          $divine = Get-ChildItem -Path ".tools/lslib" -Recurse -File |
+            Where-Object { $_.Name -ieq "Divine.exe" } |
+            Select-Object -First 1
+
+          if (-not $divine) {
+              throw "Divine.exe was not found in the downloaded LSLib release."
+          }
+
+          "path=$($divine.FullName)" | Out-File -FilePath $env:GITHUB_OUTPUT -Encoding utf8 -Append
+
+      - name: Build .pak
+        shell: pwsh
+        run: |
+          $ErrorActionPreference = "Stop"
+          New-Item -ItemType Directory -Path "build" -Force | Out-Null
+          & "${{ steps.divine.outputs.path }}" -a create-package -g bg3 -s Mods -d build/DnD55eRussian.pak
+
+      - name: Upload build artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: DnD55eRussian-pak
+          path: build/DnD55eRussian.pak
+          if-no-files-found: error
+
+      - name: Attach package to GitHub Release
+        if: github.event_name == 'release'
+        uses: softprops/action-gh-release@v2
+        with:
+          files: build/DnD55eRussian.pak