refactor(test[import]) Extract _run_import_defaults to reduce boilerplate

[tony]

Summary

• Add _run_import_defaults() wrapper with test-friendly defaults for 9 kwargs
• Replace all 28 _run_import() call sites, keeping only kwargs that differ from defaults
• Parameterize 3 structurally identical --sync/--prune test pairs using typing.NamedTuple

Net reduction: -208 lines (436 removed, 228 added). Test count unchanged (77 tests in file).

Test plan

• uv run ruff check . — all checks passed
• uv run ruff format . — no changes needed
• uv run mypy — no issues found
• uv run py.test -vvv — 1173 passed

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.51%. Comparing base (bdfaa95) to head (d648cdc).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #529   +/-   ##
=======================================
  Coverage   83.51%   83.51%           
=======================================
  Files          29       29           
  Lines        3645     3645           
  Branches      726      726           
=======================================
  Hits         3044     3044           
  Misses        386      386           
  Partials      215      215           

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[tony]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

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