unify k8s naming: drop be/fe split, single switchboard deployment

- k8s/backend.yaml → k8s/switchboard.yaml (already renamed)
- Deployment/Service name: switchboard-be → switchboard
- Removed component:backend labels (single image, no component split)
- Ingress: all paths route to switchboard service on :8080
- CI: updated manifest render, apply, and rollout references
- Removed stale extractor sidecar and extraction env vars
- Updated CHANGELOG and ROADMAP with CI fixes and design decisions

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/ci.yaml

@@ -673,7 +673,7 @@ jobs:
             envsubst < k8s/storage-pvc.yaml > /tmp/storage-pvc.yaml
           fi
 
-          envsubst < k8s/backend.yaml  > /tmp/backend.yaml
+          envsubst < k8s/switchboard.yaml  > /tmp/switchboard.yaml
           envsubst < k8s/middleware-retry.yaml > /tmp/middleware-retry.yaml
           envsubst < k8s/ingress.yaml  > /tmp/ingress.yaml
 
@@ -687,7 +687,7 @@ jobs:
             echo "  ⚠ STORAGE_CLASS not set — file storage disabled"
           fi
 
-          kubectl apply -f /tmp/backend.yaml
+          kubectl apply -f /tmp/switchboard.yaml
 
           # Traefik retry middleware (v0.28.8) — requires RBAC for traefik.io CRDs.
           # First-time setup: kubectl apply -f k8s/rbac-traefik.yaml (cluster admin)
@@ -718,14 +718,14 @@ jobs:
           SUFFIX: ${{ steps.setup.outputs.DEPLOY_SUFFIX }}
           ENV: ${{ steps.setup.outputs.ENVIRONMENT }}
         run: |
-          kubectl rollout restart deployment/switchboard-be${SUFFIX} -n ${NAMESPACE}
-          kubectl rollout status deployment/switchboard-be${SUFFIX} -n ${NAMESPACE} --timeout=180s
+          kubectl rollout restart deployment/switchboard${SUFFIX} -n ${NAMESPACE}
+          kubectl rollout status deployment/switchboard${SUFFIX} -n ${NAMESPACE} --timeout=180s
 
           echo ""
           echo "━━━ Pod Status ━━━"
           kubectl get pods -n ${NAMESPACE} -l app=switchboard,env=${ENV}
 
-          READY=$(kubectl get deployment switchboard-be${SUFFIX} -n ${NAMESPACE} -o jsonpath='{.status.readyReplicas}')
+          READY=$(kubectl get deployment switchboard${SUFFIX} -n ${NAMESPACE} -o jsonpath='{.status.readyReplicas}')
 
           if [[ "${READY:-0}" -gt 0 ]]; then
             echo "✅ Healthy: ${READY} pods ready"