Preserve search listeners after replace (fix #282773)

[MohamedEmirHajji]

Solution Summary for #282773

Problem: After Replace All, calling clear() disposed all file match objects and their model listeners, so when users undo, the changes weren't detected and the Replace All button stayed disabled.

Solution: Remove the clear() call and instead force immediate match updates via forceUpdateMatches(), which:

1. Preserves folder/file match structure and model listeners
2. Immediately re-searches all files (finding 0 matches after replacement)
3. Batches all change events to avoid UI storms
4. Allows undo operations to be detected since listeners remain active

Trade-off: Slightly slower with large result sets (requires re-searching files) compared to the instant clear(), but necessary to maintain the infrastructure for undo detection.