[baylesj]

Addresses #342 (part of #341).

Summary

• §2.1 Agent Discovery Requirements (Inline Issue 1): Defines abstract discovery requirements (presence/reachability, endpoint parameters, human-readable discovery name, metadata change signaling, and power-saving state caching).
• §2.2 Transport Layer Requirements (Inline Issue 2, incorporating Inline Issues 5, 6, 7): Defines abstract transport requirements (mutual authentication & confidentiality, persistent authenticated peer identity, context isolation for private browsing, ordered/independent CBOR message delivery, connection lifecycle & error signaling, power-saving disconnect/reconnect, and <45 ms lip-sync latency).
• §5 & §7 Presentation and Remote Playback Protocols (Inline Issues 5, 6, 7 + §5.1 / §7.2): Moves power-saving QUIC disconnect/reconnect and 45 ms latency notes into [[#requirements-transport]], and replaces "mDNS, QUIC" in §5.1 and §7.2 with references to [[#requirements-discovery]] and [[#requirements-transport]].
• §11 Security and Privacy (Inline Issues 13, 14, 15, 16): Updates Private Browsing Mode (§11.2.4), Presentation API Considerations (§11.3), Remote Playback API Considerations (§11.4), and Instance and Display Names (§11.6.1) to reference generic discovery and transport requirements rather than DNS-SD and TLS-secured QUIC connections.