DLNA/UPnP: Media Renderer (phones/apps cast to the TV) and Media Server (browse the library from other devices); AirPlay/Google Cast receivers recorded as post-v1 research

Epic: #113 · Milestone: MC8 — Library & services

Tasks

• SSDP discovery/advertise over UDP multicast; device description XML; SOAP control endpoints on the HTTP server from #100.
• Renderer: AVTransport (SetAVTransportURI/Play/Pause/Seek/Stop), RenderingControl (volume/mute), event subscriptions (GENA); plays URLs through #85.
• Server: ContentDirectory browse/search over the library DB; HTTP range serving of files.
• Post-v1 research notes: AirPlay 2 (mDNS _airplay._tcp, pairing, FairPlay constraints — likely infeasible legally/technically without Apple's keys; audio-only AirPlay 1 receivers exist in the open), Google Cast (requires Google-signed certs for official senders → likely out). Document the verdict in the ADR rather than promising it.

Acceptance

A phone DLNA controller app plays a video on the Pi; a DLNA client on the Mac browses the library.

Size: M · Depends on: #105, #100, #85 · Blocks: —