Rename build workflow to sonarqube; remove CI

Rename .github/workflows/build.yml to .github/workflows/sonarqube.yml (content unchanged) and delete the legacy .github/workflows/ci.yml workflow. Update .github/copilot-instructions.md to reference sonarqube.yml so documentation matches the new workflow filename.

Author: Snufxander

.github/copilot-instructions.md

@@ -153,7 +153,7 @@ public static class MyResource
 ## GitHub Actions
 
 - **build-dlls.yml** — Builds Debug and Release DLLs on push/PR, uploads as artifacts
-- **build.yml** — SonarQube analysis workflow
+- **sonarqube.yml** — SonarQube code quality analysis workflow
 
 ## CESDK Submodule