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/services/agent-tool-args.ts

@@ -0,0 +1,16 @@
+/** Shared argument validation for agent tool implementations. */
+
+export function requireString(value: unknown, field: string): string {
+  if (typeof value !== "string" || !value.trim()) throw new Error(`"${field}" is required.`);
+  return value.trim();
+}
+
+export function optionalString(value: unknown): string | null {
+  return typeof value === "string" && value.trim() ? value.trim() : null;
+}
+
+export function optionalStringArray(value: unknown, field: string): string[] {
+  if (value === undefined) return [];
+  if (!Array.isArray(value)) throw new Error(`"${field}" must be an array.`);
+  return value.map((item, index) => requireString(item, `${field}[${index}]`));
+}