Lisandro/v3 websockets in chsarp

[lisandroct]

Description of Changes

Re-implements #4763 on top of latest master and .NET 10 support.

There are 4 PRs related to v3 WebSocket API:

1. v3 websocket transport protocol #4761: Introduced Rust/server v3 websocket transport.
2. Update C# sdk to use v3 websocket api #4763: Attempted to update C# SDK to use v3, but never merged.
3. Update typescript sdk to use v3 websocket api #4784: Updated TypeScript SDK to use v3.
4. Batch websocket responses using the v3 protocol #5061: Refined server-side v3 batching behavior.

#4763 had changes in the Rust side that are already in master and relied on old batching behavior (that changed with #5061).

#4763's description should still be valid and apply.

API and ABI breaking changes

Same as #4763:

None. Existing servers that only support v2 continue to work because the SDK falls back during handshake.

Expected complexity level and risk

Same as #4763:

The main risks are:

• preserving message ordering when multiple logical messages share one v3 frame
• preserving fallback behavior for v2
• keeping the capped batching behavior from starving other websocket work
• keeping WebGL protocol negotiation and callback marshalling correct

The risk is limited by keeping the existing v2 logical message pipeline intact underneath the new transport layer.

Testing

Same as #4763:

Integration tests for v3 and v2 fallback