Add world tracking, fix add-by-name UX, polish layout

- Store each player's home world (from the context-menu target and party
  list) to disambiguate same-name players across worlds; shown in the
  list rows, detail panel, and party alerts. Matching prefers content ID,
  then name+world when several entries share a name.
- Add-by-name: Enter now submits (IsItemDeactivatedAfterEdit), the field
  clears on success, empty input gets feedback, and 'Name [World]' syntax
  captures a world for manually added players.
- Layout: 12px padding between the list and detail columns; tag
  checkboxes laid out two per row.