encore build docker hangs silently (or is extremely slow?) when bundle_source: true is enabled

When bundle_source: true is set in encore.app, encore build docker hangs indefinitely at the "compiling Encore application" step with no output, errors, or progress indication (output stops at: 11:04AM INF compiling Encore application for linux/arm64)

Environment

• Encore CLI: v1.53.2
• Go: 1.25.5
• OS: macOS darwin/arm64 (Apple M1 Silicon)
• Project size: ~15MB

Steps to Reproduce

1. Set bundle_source: true in encore.app
2. Run encore build docker --skip-config --arch arm64 test:local
3. Observe output stops at: 11:04AM INF compiling Encore application for linux/arm64
4. Build never completes (waited 10+ minutes)