Expose SGM memory for RetroAchievements

see RetroAchievements/rcheevos#350

src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.Memory.cs

@@ -371,7 +371,6 @@ public ChanFMemFunctions(IDebuggable debuggable, MemoryDomain vram)
 		// these consoles will use part of the system bus at an offset
 		private static readonly Dictionary<ConsoleID, (uint Start, uint Size)[]> UsePartialSysBus = new()
 		{
-			[ConsoleID.Colecovision] = [ (0x6000u, 0x400u) ],
 			[ConsoleID.SG1000] = [ (0xC000u, 0x2000u), (0x2000u, 0x2000u), (0x8000u, 0x2000u) ],
 		};
 
@@ -542,6 +541,11 @@ void TryAddDomain(string domain, uint? size = null, uint addressMangler = 0)
 						mfs.Add(new(domains["Work Ram Low"], 0, domains["Work Ram Low"].Size, 1));
 						mfs.Add(new(domains["Work Ram High"], 0, domains["Work Ram High"].Size, 1));
 						break;
+					case ConsoleID.Colecovision:
+						mfs.Add(new(domains["Main RAM"], 0, domains["Main RAM"].Size));
+						TryAddDomain("SGM Low RAM");
+						TryAddDomain("SGM High RAM");
+						break;
 					case ConsoleID.Intellivision:
 						// special case
 						mfs.Add(new NullMemFunctions(0x80));