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[popsiclelmlm]

Fixes #2614.

This keeps resilient parsing from evaluating parameter defaults, default maps, or callbacks while shell completion resolves the command context. That matches the documented behavior for resilient parsing and avoids slow or side-effectful default/callback code during tab completion.

Changes:

• skip default/default_map lookup while resilient parsing is active
• skip parameter callbacks while resilient parsing is active, including missing boolean flags
• add shell completion regression tests
• add a changelog entry

Tests:

• uv run --locked --no-default-groups --group tests pytest tests/test_shell_completion.py -q
• uv run --locked --no-default-groups --group tests pytest tests/test_shell_completion.py tests/test_options.py tests/test_defaults.py tests/test_context.py -q
• uv run --locked --no-default-groups --group tests pytest -q
• git diff --check