Remove TrimmingHelper, use autosdk trim CLI instead

Remove TrimmingHelper project from solution and helpers directory.
Trimming/NativeAOT validation is now done via `autosdk trim` CLI command.
Add trim-check CI job to workflow. Add .autosdk-trim/ to .gitignore.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: HavenDV

.github/workflows/dotnet.yml

@@ -21,6 +21,22 @@ jobs:
     secrets:
       nuget-key: ${{ secrets.NUGET_KEY }}
 
+  trim-check:
+    name: Trimming Check
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v4
+
+      - name: Install AutoSDK CLI
+        run: dotnet tool install --global autosdk.cli --prerelease
+
+      - name: Run trimming check
+        run: autosdk trim src/libs/Reka/Reka.csproj
+
   release:
     name: Release
     runs-on: ubuntu-latest

.gitignore

@@ -400,3 +400,6 @@ FodyWeavers.xsd
 # JetBrains Rider
 *.sln.iml
 /.idea/
+
+# AutoSDK trimming check temp directory
+.autosdk-trim/

Reka.slnx

@@ -1,7 +1,4 @@
 <Solution>
-  <Folder Name="/helpers/">
-    <Project Path="src/helpers/TrimmingHelper/TrimmingHelper.csproj" />
-  </Folder>
   <Folder Name="/libs/">
     <File Path="src/libs/Directory.Build.props" />
     <Project Path="src/libs/Reka/Reka.csproj" />