Promote AgentCompany-New to the repository root and retire the old app

The legacy application - its src, tests, landing site, promo assets, docs,
release tooling, CI workflows, and root configs - leaves the tree; it stays
reachable in history. Everything under AgentCompany-New moves up unchanged:
same package name, so the production userData/database path is untouched,
and e2e/build scripts already resolved paths relative to the project. The
developer cred.txt stays gitignored at its new location. Full verify:ci
passes from the new root.

src/main/app/window-security.ts

@@ -0,0 +1,17 @@
+import type { BrowserWindow } from "electron";
+
+export function attachMainWindowSecurity(win: BrowserWindow, devServerOrigin: string | null): void {
+  win.webContents.setWindowOpenHandler(() => ({ action: "deny" }));
+  const blockNavigation = (event: Electron.Event, url: string): void => {
+    if (devServerOrigin && url.startsWith(devServerOrigin)) return;
+    if (url.startsWith("file://")) return;
+    event.preventDefault();
+  };
+  win.webContents.on("will-navigate", blockNavigation);
+  win.webContents.on("will-redirect", blockNavigation);
+  // The first-party renderer never asks for camera, microphone, geolocation,
+  // notifications, and the like, so deny every permission outright — matching
+  // the provider sign-in windows — rather than leaving the default allow.
+  win.webContents.session.setPermissionRequestHandler((_webContents, _permission, callback) => callback(false));
+  win.webContents.session.setPermissionCheckHandler(() => false);
+}