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.

tests/unit/external-url.test.ts

@@ -0,0 +1,14 @@
+import { describe, expect, test } from "vitest";
+import { normalizeExternalBrowserUrl } from "../../src/main/app/external-url";
+
+describe("external browser URL validation", () => {
+  test("normalizes HTTPS URLs and preserves query strings", () => {
+    expect(normalizeExternalBrowserUrl("https://example.com/docs?q=agent")).toBe("https://example.com/docs?q=agent");
+  });
+
+  test("rejects non-HTTPS and credential-bearing URLs", () => {
+    expect(() => normalizeExternalBrowserUrl("http://example.com")).toThrow("External URLs must use HTTPS.");
+    expect(() => normalizeExternalBrowserUrl("mailto:security@example.com")).toThrow("External URLs must use HTTPS.");
+    expect(() => normalizeExternalBrowserUrl("https://user:token@example.com")).toThrow("External URLs must not include credentials.");
+  });
+});