custom prompts are not loaded when they are symlinks

Question

### What version of Codex is running?

codex-cli 0.34.0

### Which model were you using?

_No response_

### What platform is your computer?

_No response_

### What steps can reproduce the bug?

* create symlinks in ~/.codex/prompts linking to valid md files
* open codex and see that the slash commands don't include the prompts corresponding to the symlink files

### What is the expected behavior?

_No response_

### What do you see instead?

_No response_

### Additional information

_No respo