fix(notes): update folder selection when moving notes between folders

[gabrielste1n]

Summary

• Fix bug where drag-and-dropping a note into a different folder didn't update the sidebar selection — previously required a page refresh.
• If the moved note is the active note, activeFolderId now follows it (the folder-change effect in useFolderManagement re-loads notes and preserves activeNoteId, so the editor stays on the same note while the sidebar selection moves to the destination folder).
• Otherwise, the note is removed from the current folder's list since it no longer belongs there.
• Same logic applies uniformly to all three move paths: drag-drop, the editor metadata-row folder picker, and the list-item context menu.

Test plan

• Drag a note (the currently active one) into a different folder → editor stays on the note, sidebar selection moves to the destination folder.
• Drag a non-active note into a different folder → it disappears from the current folder's list; sidebar stays on current folder.
• Move the active note via the metadata-row folder picker → editor stays on note, sidebar follows.
• Move a note via the list-item context menu → behaves per the two cases above.
• Folder counts in the sidebar refresh after each move.