feat(Sky): Add debug DAP message and custom editor save event handlers

Add two new SkyBridge handlers to bridge VS Code workbench services:

1. `sky://debug/dap-message` - Forwards parsed DAP frames from Mountain's spawned debug-adapter stdout into a `cel:debug:dap-message` DOM event. This enables a future RawDebugSession shim to subscribe and correlate responses by `request_seq` without re-implementing DAP framing.

2. `sky://customEditor/saved` - Dispatches `cel:customEditor:saved` after Mountain's `OnSaveCustomDocument` reverse-RPC succeeds. While the workbench's dirty indicator updates via `IFileService.writeFile`, observers like gitlens diff overlays listen for this explicit "extension save callback completed" signal.

Both handlers integrate with the existing custom event system, extending the bridge pattern established by recent SCM and debug session lifecycle handlers.

Author: NikolaRHristov

Source/Function/SkyBridge.ts

@@ -2255,6 +2255,30 @@ export async function InstallSkyBridge(): Promise<void> {
 		);
 	});
 
+	// Forward parsed DAP frames from the spawned debug-adapter's stdout
+	// (Mountain `Environment/DebugProvider.rs::StartDebugging` stdout-reader
+	// task) into a `cel:debug:dap-message` DOM event. The workbench's
+	// `RawDebugSession` correlates responses by `request_seq`; routing the
+	// raw `{ sessionId, message }` shape here lets a future RawDebugSession
+	// shim subscribe and forward without re-implementing DAP framing.
+	await Register("sky://debug/dap-message", (Payload: any) => {
+		document.dispatchEvent(
+			new CustomEvent("cel:debug:dap-message", { detail: Payload }),
+		);
+	});
+
+	// Custom editor save lifecycle: Mountain emits `sky://customEditor/saved`
+	// after `OnSaveCustomDocument` reverse-RPC succeeds. Workbench's dirty-
+	// indicator already updates from the `IFileService.writeFile` flow the
+	// extension drives, but observers (gitlens diff overlays, change-tracking
+	// surfaces) listen on `cel:customEditor:saved` for the explicit
+	// "extension save callback completed" signal.
+	await Register("sky://customEditor/saved", (Payload: any) => {
+		document.dispatchEvent(
+			new CustomEvent("cel:customEditor:saved", { detail: Payload }),
+		);
+	});
+
 	// ---- Webview extensions ----
 	// Extension-initiated webview content updates. The canonical channel
 	// is the kebab-case `sky://webview/set-html` (see `SkyEvent.ts` for