.git_commit_msg

feat(wave120): purge 188 dead globals, 4 hot-path blocks (-376 lines, v9.7.0)

Delete 188 module-level _var = None globals never assigned non-None.
Permanent-None placeholders from Waves 41-51.

Removal scope:
- 188 module-level _var = None declarations
- 158 standalone `global _var` stmts in main()
- 4 dead hot-path if-blocks (pd_disaggregator x3, speculative_streamer,
  chunk_kv_manager, flash_attn3 status row)

False positives excluded (live via globals() dict):
  _lazy_expert, _structured_sparsity

Lines: 5207 to 4831 (-376)

Add tests/test_wave120_dead_global_purge.py (128 tests):
- 60 parametrized spot-checks (module-level + global-stmt absence)
- 4 hot-path absence assertions
- 2 live-global preservation checks
- 1 line-count gate (< 5000)
- 1 sentinel: test_no_new_dead_globals

Update test_wave75/test_wave78: remove _flash_attn3 patch target.
Add dev/wave120_purge.py + dev/dead_globals_analysis.py for reuse.