[ty] Ensure first-party search paths always appear in a sensible order (#20629)
This PR ensures that we always put `./src` before `.` in our list of
first-party search paths. This better emulates the fact that at runtime,
the module name of a file `src/foo.py` would almost certainly be `foo`
rather than `src.foo`.
I wondered if fixing this might fix
https://github.com/astral-sh/ruff/pull/20603#issuecomment-3345317444. It
seems like that's not the case, but it also seems like it leads to
better diagnostics because we report much more intuitive module names to
the user in our error messages -- so, it's probably a good change
anyway.
ruff
8664842d - [ty] Ensure first-party search paths always appear in a sensible order (#20629)
