fix: enable BuildKit for P2 image builds

backend/scripts/p2-acceptance.mjs

@@ -843,7 +843,7 @@ async function buildCoreImage(ctx) {
   const build = await runCommand({
     executable: ctx.executables.dockerPath,
     argv: ["build", "-f", join(ctx.repositoryRoot, "docker", "core.Dockerfile"), "-t", tag, ctx.repositoryRoot],
-    env: ctx.execEnv,
+    env: { ...ctx.execEnv, DOCKER_BUILDKIT: "1" },
     maxOutputBytes: 4 * 1024 * 1024,
   });
   if (build.exitCode !== 0) throw new Error(`core image build failed: ${build.stderr || build.stdout}`);

scripts/build-thothctl.sh

@@ -1,5 +1,6 @@
 #!/usr/bin/env bash
 set -euo pipefail
+export DOCKER_BUILDKIT=1
 
 repository_root=$(cd "$(dirname "$0")/.." && pwd)
 output_directory="${THT_THOTHCTL_OUTPUT_DIRECTORY:-$repository_root/dist/thothctl}"