af open should work from any directory, not just workspace root

[waleedkadous]

Bug

af open currently restricts usage to the workspace root directory. This is unnecessarily limiting — it should work from anywhere (inside worktrees, subdirectories, etc.).

Expected

af open <file> works regardless of the current working directory.

Actual

af open fails or is restricted when run from outside the workspace root.

[waleedkadous]

On it! Working on a fix now.