v2.9.0

New

• Review mode — replay PGN games with live multi-PV engine analysis and a threat view (opponent's threat via null move), with move navigation.
• Drag-and-drop piece moves, with the dragged piece following the cursor.
• Per-role engine managers (Opponent / Analysis / Threat / Adviser): pick an engine, configure its UCI options per role, save / select / delete — persisted.
• Player manager (User menu): add, select, delete player names — persisted.
• Topical, mode-aware Help menu + About dialog.
• Settings persistence (pecg_settings.json): time-forfeit adjudication option, save-time-left, review analysis/threat time caps.

Improved / Changed

• Migrated PySimpleGUI → FreeSimpleGUI.
• Engine kept alive between moves (faster play; quits on game over / neutral).
• Engine options (Edit → Modify) dialog is now scrollable + screen-capped for engines with many options.
• Updated deps (chess 1.11.2, pyperclip 1.11.0); expanded README; About shows LGPL-3.0.