Improve mithril package creation so that they are stable and not overlapping packages are created.

Summary by CodeRabbit

• New Features

  • Resume block packaging from the last checkpoint to continue interrupted operations.
  • In-memory archive creation with deterministic archive naming and zeroed timestamps for reproducible archives.
  • Packaging now operates on structured block identifiers to improve archive organization and resume behavior.
  • Enhanced logging around resume points and archive handling.

• Bug Fixes

  • Prevents duplicate archives and correctly retains or replaces tail archives during packaging.

• Tests

  • Added tests for archive naming, boundary parsing, latest-selection, and resume-point logic.