Feature/qapp reticulum networking

[Philreact]

• Add Q-App Reticulum networking and backend connection permissions, including lifecycle cleanup and authenticated request handling.
• Add private QUIC-over-MASQUE transport with relay discovery, access tickets, connection pooling, independent streams, prioritization, bounded buffering, and MoQ media delivery.
• Improve realtime media reliability with per-stream failure isolation and support for larger incoming MoQ objects.
• Add Q-App screen-capture permission flow and native media-picker integration.
• Add permissioned Q-App file saves, including streamed downloads to the user’s selected destination.
• Move desktop Q-Apps from iframes to isolated Electron guest sessions with per-app persistent storage, strict navigation/origin controls, and blocked WebRTC.
• Add local BTC, LTC, DOGE, DGB, and RVN transaction planning/signing so private extended keys are never sent to Core.
• Support locally signed BTC-family sends and QORT buy orders through public nodes; keep all sell orders and ARRR operations restricted on public nodes.
• Add relay-access, local-wallet, private-transport, MoQ, Reticulum, guest-policy, screen-capture, and file-save coverage and documentation.