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/desktop/src/diagnostics/app-logs.ts

@@ -0,0 +1,17 @@
+import log from "electron-log/main";
+import { tailFile } from "./tail-file.js";
+
+const APP_LOG_TAIL_LINES = 100;
+
+export interface DesktopAppLogs {
+  logPath: string;
+  contents: string;
+}
+
+export function getDesktopAppLogs(): DesktopAppLogs {
+  const logPath = log.transports.file.getFile().path;
+  return {
+    logPath,
+    contents: tailFile(logPath, APP_LOG_TAIL_LINES, { throwOnReadError: true }),
+  };
+}