test(cli): cover rm purge default option

[overtrue]

Summary

This adds a focused unit test for the default rm --purge behavior.

The recent force-delete support already had coverage for the enabled path and integration coverage for permanent deletion behavior, but the opposite branch was still untested: when --purge is not supplied, the CLI should keep force_delete disabled in the delete request options. This PR adds that missing assertion without changing production code.

Root Cause

PR #82 introduced the purge flag and added a unit test for the true case only. That left the default false branch unguarded, even though the flag wiring is security-sensitive because it controls whether RustFS permanent deletion headers are sent.

Fix

Add test_delete_request_options_disable_force_delete_by_default in crates/cli/src/commands/rm.rs and assert that delete_request_options keeps force_delete set to false when purge is not provided.

Validation

make pre-commit is not defined in this checkout, so I ran the repository's required checks directly:

• cargo fmt --all --check
• cargo clippy --workspace -- -D warnings
• cargo test --workspace
• cargo test -p rustfs-cli test_delete_request_options_disable_force_delete_by_default

Notes

I also checked for an existing open PR on this topic and avoided duplicating the parser coverage already proposed in PR #98.