Remove legacy Java/Groovy tree; expand unit tests; bump to 2.0.1

- Drop legacy migmap sources and assets: post/, data/ (legacy blast DBs),
  src/main, src/test, build.gradle, .travis.yml, migmap, travis_cli_test.sh.
  The Python rewrite (src/arda + src/_markup) is now the whole repo.
- Add unit tests for the CLI surface (info/split/merge/slurm), AIRR output
  assembly, the library adapter's input normalization, and load_j_frames;
  fast-suite line coverage 56% -> 63% (cli 0->80%, adapter/airr_out 0->100%).
- Bump version 0.1.0 -> 2.0.1 (pyproject, __init__, docs) succeeding the
  legacy 1.x Java line; document 'arda slurm' in the skill CLI block.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: mikessh