colima: fix KeepAlive to prevent process accumulation on macOS

Change KeepAlive from boolean true to SuccessfulExit dictionary in the LaunchAgent configuration.
When colima fails to start (e.g., disk already attached), the boolean true setting causes
launchd to immediately restart it, spawning orphaned limactl usernet processes with each
restart.

Using SuccessfulExit = true ensures the service only restarts on clean exits (exit code 0),
preventing the aggressive restart loop that accumulates orphaned processes.

modules/services/colima.nix

@@ -202,7 +202,9 @@ in
             "--activate=${if profile.isActive then "true" else "false"}"
             "--save-config=false"
           ];
-          KeepAlive = true;
+          KeepAlive = {
+            SuccessfulExit = true;
+          };
           RunAtLoad = true;
           EnvironmentVariables.PATH = lib.makeBinPath [
             cfg.package

tests/modules/services/colima/darwin/expected-agent.plist

@@ -8,7 +8,10 @@
 		<string>@colima@/bin:@perl@/bin:@docker@/bin:@openssh@/bin:@coreutils@/bin:@curl@/bin:@bashNonInteractive@/bin:@DarwinTools@/bin</string>
 	</dict>
 	<key>KeepAlive</key>
-	<true/>
+	<dict>
+		<key>SuccessfulExit</key>
+		<true/>
+	</dict>
 	<key>Label</key>
 	<string>org.nix-community.home.colima-default</string>
 	<key>ProgramArguments</key>