ci: add CI workflow (build, ReSharper format check, test + coverage)

Adapted from the shared sample: builds Release on ubuntu + windows, runs the
ReSharper ReformatAndReorder gate (matching the local pre-push hook), and runs the
test suite with Cobertura coverage. Triggers on pushes to develop and on PRs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: HandyS11

.github/workflows/CI.yml

@@ -0,0 +1,54 @@
+name: CI
+
+permissions:
+  contents: read
+
+on:
+  push:
+    branches:
+      - develop
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ ubuntu-latest, windows-latest ]
+      fail-fast: false
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v5
+        with:
+          dotnet-version: '10.0.x'
+          cache: true
+          cache-dependency-path: Directory.Packages.props
+
+      - name: Restore dependencies
+        run: dotnet restore
+
+      - name: Build
+        run: dotnet build --no-restore --configuration Release
+
+      - name: Restore tools
+        if: matrix.os == 'ubuntu-latest'
+        run: dotnet tool restore
+
+      - name: Check formatting (ReSharper)
+        if: matrix.os == 'ubuntu-latest'
+        run: |
+          dotnet jb cleanupcode RustPlusBot.slnx --profile="ReformatAndReorder" --no-build --verbosity=ERROR
+          git diff --exit-code
+
+      - name: Test
+        run: dotnet test --no-build --configuration Release --verbosity normal --collect:"XPlat Code Coverage" --results-directory ./coverage
+
+      - name: Upload coverage reports
+        if: matrix.os == 'ubuntu-latest'
+        uses: actions/upload-artifact@v7
+        with:
+          name: coverage-reports
+          path: ./coverage/**/coverage.cobertura.xml
+          retention-days: 14