### Motivation
- Git subcommand matching was being classified as "dangerous" and caused
benign developer workflows (for example `git push --force-with-lease`)
to be blocked by the preflight policy.
- The change aligns behavior with the intent to reserve the dangerous
checklist for truly destructive shell ops (e.g. `rm -rf`) and avoid
surprising developer-facing blocks.
### Description
- Remove git-specific subcommand checks from
`is_dangerous_to_call_with_exec` in
`codex-rs/shell-command/src/command_safety/is_dangerous_command.rs`,
leaving only explicit `rm` and `sudo` passthrough checks.
- Deleted the git-specific helper logic that classified `reset`,
`branch`-delete, `push` (force/delete/refspec) and `clean --force` as
dangerous.
- Updated unit tests in the same file to assert that various `git
reset`/`git branch`/`git push`/`git clean` variants are no longer
classified as dangerous.
- Kept `find_git_subcommand` (used by safe-command classification)
intact so safe/unsafe parsing elsewhere remains functional.
### Testing
- Ran formatter with `just fmt` successfully.
- Ran unit tests with `cargo test -p codex-shell-command` and all tests
passed (`144 passed; 0 failed`).
------
[Codex
Task](https://chatgpt.com/codex/tasks/task_i_698d19dedb4883299c3ceb5bbc6a0dcf)
## Summary
This should rarely, if ever, happen in practice. But regardless, we
should never provide an empty list of `commands` to ExecPolicy. This PR
is almost entirely adding test around these cases.
## Testing
- [x] Adds a bunch of unit tests for this
