feat: configure /ready/synced block tolerance

[apoorvsadana]

Summary

• make the /ready/synced block-lag tolerance configurable
• add PATHFINDER_READY_SYNCED_BLOCK_TOLERANCE and --monitor.ready-synced-block-tolerance
• retain the existing default of 6 blocks
• test the configured strict boundary and document the setting
• move manual Docker builds to blacksmith-8vcpu-ubuntu-2204
• allow an explicit Pathfinder version for tag-less fork builds
• publish Karnot images to ghcr.io/karnotxyz/pathfinder using GITHUB_TOKEN

Validation

• git diff --check
• GitHub Actions rustfmt and lightweight checks passed on the initial commit
• local compilation intentionally skipped; validation delegated to GitHub Actions as requested
• Blacksmith image build: https://github.com/karnotxyz/pathfinder/actions/runs/29615853225

This PR is based directly on base/pathfinder-v0.22.2, which points to the devnet tag commit.