Redmine

This is my first contribution to Redmine, so I apologize in advance if anything is incorrect or missing.

I have created a patch based on the fix proposed in the description.

Fix:
Changed the sortable value for the parent_id column in app/models/project_query.rb from "#{Project.table_name}.lft ASC" to "#{Project.table_name}.parent_id".

The embedded ASC in the original lft ASC string caused Redmine's append_order method to treat it as a fixed-direction expression, ignoring the user-selected sort direction entirely. As a result, both ascending and descending clicks produced the same order.

Tests added:

test_sort_by_parent_id_asc_should_not_include_fixed_direction — verifies ASC direction is applied and lft is no longer used
test_sort_by_parent_id_desc_should_apply_desc_direction — verifies DESC direction is now correctly applied (this failed before the fix)
Screenshots showing the before/after behavior are attached.

I found that the previous patch I submitted introduced a regression in
`test_index_as_list_should_indent_projects`. I have revised the fix and attached
`patch-issue-43524-fix-project-sort-by-parent-v2.diff`.

Root cause:
The `sortable` value `"#{Project.table_name}.lft ASC"` has a hardcoded `ASC` suffix,
which causes Redmine's `append_order` to treat it as a fixed-direction expression and
ignore the user-selected sort direction entirely.

Why not use `parent_id`:
Changing to `parent_id` fixed the direction bug but broke project indentation.
`grouped_project_list` in `projects_helper.rb` relies on tree traversal order
(parents before children) to compute indent depth. Sorting by `parent_id` does not
guarantee this order.

Fix:
In `app/models/project_query.rb`, changed `sortable` from `"#{Project.table_name}.lft ASC"`
to `"#{Project.table_name}.lft"` (removing the hardcoded `ASC` suffix) and `default_order`
from `'desc'` to `'asc'`.
This allows the user-chosen direction to be applied while preserving tree order for
proper indentation.

Tests:
- `test/functional/projects_controller_test.rb`: Updated `test_index_as_list_should_indent_projects`
to use `parent_id:asc` (ASC maintains tree traversal order, so indentation works correctly)
- `test/unit/project_query_test.rb`: Added `test_sort_by_parent_id_asc_should_apply_asc_direction`
— verifies `lft ASC` is used for ASC
- `test/unit/project_query_test.rb`: Added `test_sort_by_parent_id_desc_should_apply_desc_direction`
— verifies `lft DESC` is used for DESC (this failed before the fix when direction was hardcoded to ASC)