fix: postgres 18 default data volume change and fasttime server on arm64

[araujof]

Summary

Resolves container startup failures caused by PostgreSQL 18's new data directory structure and cross-platform compatibility issues with amd64-only images on ARM hosts.

Changes

docker-compose.yml

• PostgreSQL 18 volume compatibility: Changed postgres volume mount from /var/lib/postgresql/data to /var/lib/postgresql to align with PostgreSQL 18's new directory structure that uses pg_ctlcluster-compatible paths
• Optional fast_time_server: Made fast_time_server and register_fast_time services optional using Docker Compose profiles to prevent emulation failures on ARM platforms (Apple Silicon)
  • Added profiles: ["with-fast-time"]
  • Added documentation comment explaining ARM compatibility issues

Makefile

• Platform-aware profiles: Added automatic profile detection based on platform architecture
  • Enables with-fast-time profile automatically on linux/amd64 platforms
  • Skips fast_time_server on ARM platforms by default

Impact

Before:

• make compose-up failed with PostgreSQL 18 data directory errors
• Platform mismatch warnings for fast_time_server on ARM

After:

• Clean startup on both x86_64 and ARM platforms
• PostgreSQL 18 starts successfully with proper volume structure
• Optional fast_time_server on x86_64: docker compose --profile with-fast-time up -d
• No build or runtime errors