scanner.py: _EXPORT_LIST_PATTERN was applied line-by-line, so multi-line
export blocks like:

    export {
      Foo,
      Bar,
    }

were silently missed — Foo and Bar were never added to the exports map
and thus never flagged as unused exports (false negatives).

Fix: apply _EXPORT_LIST_PATTERN to the full file content (re.DOTALL added
for clarity; [^}] already matched newlines). Line number computed via
content.count('\n', 0, m.start()) + 1 so findings still point to the
opening 'export {' line. Single-line export { Foo, Bar } behaviour is
unchanged.

Add TestMultiLineExportList (4 tests) covering: multi-line detection,
used-name suppression, alias handling, single-line regression.

…h TestMultiLineExportList and master test suites)

…ocess tests

- Strip // comments from multi-line export lists so exports after commented
  entries are no longer silently missed (_parse_exports in scanner.py).
- Replace sys.executable subprocess probes in test_cli_edge_cases.py with
  CliRunner so the suite passes regardless of editable-install state.
- Add regression test for inline comments inside export { } blocks.