feat!: protocol v1

[zxch3n]

Upgrade the protocol to v1

• v1 appends an 8-byte Update Batch ID to every DocUpdate so peers can correlate acknowledgments.
• v1 introduces Ack (0x08) to positively confirm or reject updates; v0 relied on UpdateError messages and had no explicit success signal.
• v1 repurposes 0x06 from UpdateError to RoomError, which evicts the peer from the room until it rejoins.
• v1 shifts update status codes: ok is now 0x00, unknown moves to 0x01, and the remaining codes keep their numeric values from v0.
• v1 clarifies that a RoomError means the peer will stop receiving room traffic unless it performs a new join handshake.

Why these changes (v1)

• Reliable delivery semantics: explicit Ack for each update batch (or fragment batch) lets applications know whether a change was accepted instead of inferring success from silence.
• Clear eviction signal: RoomError distinguishes "your update failed" from "you are no longer in the room", enabling clients to stop syncing and prompt rejoin or escalation.
• Better error mapping: moving ok to 0x00 and unknown to 0x01 aligns status bytes with common success/failure conventions and leaves room for app-specific errors.
• Debuggability: 64-bit batch IDs make ACK correlation collision-resistant even on long-lived, multiplexed connections while adding negligible overhead versus the 256 KiB frame limit.

[chatgpt-codex-connector]

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