Include desktop app logs in diagnostics (#1914)

* fix(diagnostics): include desktop app logs

Settings diagnostics now collect the Electron main-process log separately from daemon.log so desktop startup and environment-probe failures are included in app reports.

* refactor(desktop): share log tail reader

* fix(diagnostics): surface desktop app log read errors

* refactor(diagnostics): tighten desktop report API

packages/app/src/desktop/daemon/desktop-daemon.ts

@@ -28,6 +28,11 @@ export interface DesktopDaemonLogs {
   contents: string;
 }
 
+export interface DesktopAppLogs {
+  logPath: string;
+  contents: string;
+}
+
 export interface DesktopPairingOffer {
   relayEnabled: boolean;
   url: string | null;
@@ -144,6 +149,17 @@ export async function getDesktopDaemonLogs(): Promise<DesktopDaemonLogs> {
   return parseDesktopDaemonLogs(await invokeDesktopCommand("desktop_daemon_logs"));
 }
 
+export async function getDesktopAppLogs(): Promise<DesktopAppLogs> {
+  const raw = await invokeDesktopCommand("desktop_app_logs");
+  if (!isRecord(raw)) {
+    throw new Error("Unexpected desktop app logs response.");
+  }
+  return {
+    logPath: toStringOrNull(raw.logPath) ?? "",
+    contents: typeof raw.contents === "string" ? raw.contents : "",
+  };
+}
+
 export async function getDesktopDaemonPairing(): Promise<DesktopPairingOffer> {
   return parseDesktopPairingOffer(await invokeDesktopCommand("desktop_daemon_pairing"));
 }