fix(FR-2491): preserve project selection when closing Fair Share settings modal without changes (#6508)

Resolves #6478 (FR-2491)

## Summary
- Fixed a bug where closing the Fair Share weight settings modal without making changes would clear the project (and domain/user) row selection in the table.
- The `onRequestClose` handler in `FairShareList.tsx` was unconditionally calling `setSelectedRows([])` on modal close, even when the modal was opened for a single-row settings edit. Now `selectedRows` is only cleared when the save was successful or when the bulk edit modal (opened via the bulk edit button) is cancelled.

## Root Cause
When a user clicked the settings icon on a single row, `selectedSingleRow` was set to open the modal. On modal close (cancel), `setSelectedRows([])` wiped the checkbox selections even though those were unrelated to the single-row edit.

## Test plan
- [ ] Select multiple projects via checkboxes in Fair Share project step
- [ ] Click the settings icon on a single project row to open the weight setting modal
- [ ] Close the modal without making changes
- [ ] Verify the checkbox selections are preserved
- [ ] Open the bulk edit modal (via the bulk edit button in the toolbar) and cancel
- [ ] Verify the checkbox selections are cleared (expected behavior for bulk edit cancel)
- [ ] Make a successful edit and verify selections are cleared after save

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Author: ironAiken2

react/src/components/FairShareItems/FairShareList.tsx

@@ -873,8 +873,8 @@ const FairShareList: React.FC = () => {
           onRequestClose={(success) => {
             if (success) {
               updateFetchKey();
+              setSelectedRows([]);
             }
-            setSelectedRows([]);
             setSelectedSingleRow(null);
             setOpenWeightSettingModal(false);
           }}