`PathList` stores both sorted paths and the original insertion order
(for display in the project panel). Previously, `PartialEq`, `Eq`, and
`Hash` were derived, which meant two `PathList` values with the same
paths but different display orderings were considered unequal.

This change replaces the derived impls with manual ones that only
compare
the sorted `paths` field, matching the semantic intent: a `PathList`
identifies a set of directories, and the display order is not part of
that identity.

Release Notes:

- N/A