Fix SIGILL crash on CPUs without AVX2 support (#70) (#71)

Fix SIGILL crash on CPUs without AVX2 support (#70) (#71)

Copy Bun binary from official oven/bun:1-slim image instead of using
the install script. The official images use baseline builds for x64,
which only require SSE4.2 and work on older/low-power CPUs like the
Intel Atom C3558R that lack AVX2 instructions.

Also fixes compatibility with updated presidio-analyzer base image:
- Use USER root for build, then switch to non-root (UID 1001) for runtime
- Fix Presidio config paths (/app/presidio_analyzer/conf/)
- Move PasteGuard to /pasteguard to avoid overwriting Presidio's /app
- Update supervisord to run without root privileges
- Update volume mount paths in docker-compose.yml and docs