test(cli): cover top-level alias parsing

[overtrue]

Summary

This change adds focused parser coverage for deprecated top-level command aliases introduced in the recent bucket CORS and event work.

Problem

The recent command surface expansion added deprecated top-level rc cors and rc event entry points alongside the nested rc bucket ... forms. Existing tests already covered the nested bucket forms and one top-level cors remove case, but two parser paths were still untested:

• rc cors get <alias/bucket> should resolve to the List command through the get alias.
• rc event list <alias/bucket> should continue to parse through the deprecated top-level entry point.

Without direct assertions, a future clap refactor could silently break these compatibility paths while leaving adjacent tests green.

Fix

The patch adds two small command parser tests in crates/cli/src/commands/mod.rs:

• cli_accepts_top_level_cors_get_alias
• cli_accepts_top_level_event_subcommand

The production code is unchanged. The diff is intentionally limited to command-surface tests around the recently added aliases.

Validation

make pre-commit is not available in this checkout because the repository does not define a pre-commit target.

The branch was validated with:

• cargo fmt --all --check
• cargo clippy --workspace -- -D warnings
• cargo test --workspace