fix: use sonar-scanner-cli container instead of npx for sonar scan

npx sonar-scanner fails on node:18-slim — no Java. Switch to dedicated
sonarsource/sonar-scanner-cli container with Java + scanner bundled.

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

vars/scanCodeQuality.groovy

@@ -1,6 +1,7 @@
 /**
- * Runs sonar-scanner via npx inside current container.
- * Must be called inside container('node') block.
+ * Runs sonar-scanner inside container('sonar') (sonarsource/sonar-scanner-cli).
+ * Must be called inside container('sonar') block.
+ * Agent pod must be created with homelabK8sAgent(withSonar: true).
  *
  * config keys:
  *   projectKey (required) - SonarQube project key
@@ -22,7 +23,7 @@ def call(Map config) {
 
     withCredentials([string(credentialsId: credId, variable: 'SONAR_TOKEN')]) {
         sh """
-            npx sonar-scanner \
+            sonar-scanner \
               -Dsonar.projectKey=${projectKey} \
               -Dsonar.sources=${sources} \
               -Dsonar.host.url=${sonarUrl} \