Add FFDec docs/tools and server-browser fixes

Add comprehensive FFDec walkthrough and short patch docs for safely adding a Multiplayer item to MainMenu.swf, plus helper scripts to extract the vanilla SWF and restore it (tools/extract_ba2.py, tools/restore-vanilla-mainmenu.ps1). Update exported MainMenu.as with a warning comment and remove an outdated exported PATCH markdown. Patch binary Interface/MainMenu.swf (updated).

Hardening fixes in the plugin: include GFx headers, avoid leaving the PrismaUI overlay focused after menu changes, only call OnBrowserHidden when the browser was actually visible, and add IsMainMenuOnMainPanel() so WatchMainMenuState ignores MainMenu when not on the MAIN_STATE. Ensure events are only dispatched when the browser is valid & visible (CanDispatchToBrowser) and make Scaleform UI hide the browser immediately during transitions. These changes prevent the overlay from staying focused during Settings transitions and stop JS events from being sent to a hidden/invalid view.

Interface/exported/scripts/MainMenu.as

@@ -1,5 +1,7 @@
 package
 {
+   // REFERENCE ONLY — edit the vanilla MainMenu.swf surgically in FFDec.
+   // Do NOT paste this entire file back into FFDec; full re-import breaks settings sub-menus.
    import Shared.AS3.BSButtonHint;
    import Shared.AS3.BSButtonHintBar;
    import Shared.AS3.BSButtonHintData;
@@ -2281,10 +2283,6 @@ package
                   "text":"$Settings_FrameCap",
                   "movieType":1,
                   "options":["$Settings_FrameCap_On","$Settings_FrameCap_60"]
-               },{
-                  "text":"$Settings_FrameCap",
-                  "movieType":1,
-                  "options":["$Settings_FrameCap_On","$Settings_FrameCap_40","$Settings_FrameCap_60"]
                },{
                   "text":"$Settings_VisualFidelity",
                   "movieType":1,