Remove --no-cache flag from Docker build

Docker layer cache is smart enough to rebuild when source changes
Speeds up builds significantly by reusing package installation layers

build_truenas.sh

@@ -47,7 +47,6 @@ ssh -A root@${TRUENAS_HOST} "cd ${BUILD_DIR} && \
 # Build Docker image on TrueNAS
 echo "Building Docker image on TrueNAS..."
 ssh -A root@${TRUENAS_HOST} "cd ${BUILD_DIR} && docker build \
-    --no-cache \
     --build-arg DOTNET_VERSION=9.0 \
     --build-arg PACKAGE_ARCH=amd64 \
     --build-arg DOTNET_ARCH=x64 \