Update typescript sdk to use v3 websocket api

[joshua-spacetime]

Description of Changes

Adds TypeScript SDK support for the v3.bsatn.spacetimedb websocket API which was added in #4761.

v3 just adds batching on top of v2, so adding support for it just required the following:

1. The client negotiates the protocol with the server and falls back to v2 if necessary
2. When v3 is negotiated, same-tick outbound client messages are batched into a single ws frame
3. Inbound v3 server frames are unwrapped into their inner v2 messages and processed in-order

Some notes on the batching behavior:

1. Outbound v3 frames are capped at 256 KiB (unless a single message exceeds the limit)
2. The SDK sends one v3 frame per flush
3. If more messages remain queued after hitting the cap, it schedules a follow-up flush on a later task instead of draining in a tight loop, so that outbound ws work doesn't starve inbound ws work or any other event-loop tasks

API and ABI breaking changes

None, v2 fallback remains supported, so existing servers that only negotiate v2 still work with the updated client.

Expected complexity level and risk

3

Constraints that must hold:

1. Same-tick sends should coalesce under v3
2. v2 should remain unaffected
3. Capped batching should not starve inbound processing
4. Server frames containing multiple logical messages must be processed in-order
5. Handshake fallback to v2 must remain correct

Testing

Added tests for the fast path and fallback behavior

[coolreader18]

LGTM

I know this isn't the topic of changes in this PR, but is there a point to having distinct Single / Batch frames? How is a Single frame different from a Batch of 1? And then you have redundant data in the binary payload: 0x01 /* <- this frame has more than 1 message */ 0x00_00_00_01 /* <- now here's how many messages this frame has */. The data in the enum tag is already communicated in the array length.

[coolreader18]

This seems unnecessary. You can just use ClientFrame / ServerFrame as types, you don't even need these type imports.

[joshua-spacetime]

How is a Single frame different from a Batch of 1?

It's not.