docs(plan): Update Current Focus to include completed Phase B

documentation/PLAN.md

@@ -60,6 +60,7 @@ Lumacs/
 - ✅ Removed unwanted GTK context menus and tooltips
 - ✅ Implemented Modeline Framework (Phase Y)
 - ✅ Centralizing Minibuffer Logic (Phase Z)
+- ✅ Keybinding System Refactoring (Phase B)
 
 ## Core Refactoring Goals