Split the flat 134-method DesktopApi interface into 12 domain
sub-interfaces (companies, agents, tasks, runs, approvals,
communication, threads, credentials, skills, budget, automation,
window) under src/shared/contracts/desktop-api/. desktop-api.ts
now intersects them to preserve the exact external flat shape;
window.agentCompany consumers and preload wiring are untouched.
