feat(rebuild): scaffold m2 whole-module run

[gowdaharshith1998-lang]

Summary

• vendor the full Apache Commons Lang 2.6 Java source corpus under tests/corpus/commons_lang_full
• add omnix rebuild --module <fqn> as a module-prefix convenience wrapper around node filtering
• document the M2 live-run protocol without running live LLM spend

Important note

• Full upstream org.apache.commons.lang.StringUtils currently parses to 177 method/constructor nodes, not the dispatch note's 27 receipts. The runbook documents this mismatch instead of filtering or fabricating a count.

Verification

• python -m ruff check src/omnix/cli.py tests/rebuild/test_cli.py tests/corpus/test_commons_lang_corpus.py
• python -m mypy src/omnix/cli.py
• pytest tests/rebuild/test_cli.py tests/corpus/test_commons_lang_corpus.py -q -> 13 passed
• pytest tests/corpus/ tests/rebuild/ -q -> 23 passed
• pytest tests/ -q --tb=line -> 749 passed, 6 skipped, 27 xfailed
• git diff --cached --check before commit
• npx gitnexus detect-changes --scope staged -> LOW risk, 0 affected processes

Notes

• GitHub Actions may remain blocked by the repository billing/quota state observed on earlier stacked PRs.
• No live LLM/API run was executed.