Fix: check secret in shell instead of workflow if condition

.github/workflows/installer_build.yml

@@ -10,6 +10,7 @@ on:
     paths:
       - ".github/workflows/installer_build.yml"
       - "src/main/csharp/net/eagle0/clients/win/installer/**"
+  workflow_dispatch:
 
 permissions:
   contents: read
@@ -29,6 +30,19 @@ jobs:
         with:
           dotnet-version: '8.0.x'
 
+      - name: Inject manifest public key
+        env:
+          MANIFEST_PUBLIC_KEY: ${{ secrets.MANIFEST_PUBLIC_KEY }}
+        run: |
+          if [ -n "$MANIFEST_PUBLIC_KEY" ]; then
+            CONFIG_FILE="src/main/csharp/net/eagle0/clients/win/installer/EagleInstaller/configuration.txt"
+            echo "manifest_public_key = $MANIFEST_PUBLIC_KEY" >> "$CONFIG_FILE"
+            echo "Injected manifest public key into configuration.txt"
+            cat "$CONFIG_FILE"
+          else
+            echo "MANIFEST_PUBLIC_KEY not set, skipping injection"
+          fi
+
       - name: Restore dependencies
         run: dotnet restore src/main/csharp/net/eagle0/clients/win/installer/EagleInstaller/EagleInstaller.csproj