test/suite has grown to 830+ files with hooks, utilities, and test cases all at the top level, making navigation difficult and giving no structural signal about which files are support infrastructure vs. test cases.

Two subdirectories are introduced:

• hooks/ — all hook_*.py files (8 files)
• helpers/ — shared test utilities and framework files (18 files: helper*.py, _util.py, *_helper.py, wt.py, suite_subprocess.py)

Import paths in run.py and all affected test_*.py files are updated accordingly.