[WIP] Update configurable WebSocket buffer sizes for Nostr events

[Copilot]

Plan to Fix Test Assertion Handling in StandardWebSocketClientMultiMessageTest

This PR addresses the feedback that test assertions running in background threads are not properly surfaced to JUnit.

Changes Needed

• Refactor testAccumulatesMessagesUntilEose to capture exceptions from worker thread
• Refactor testCompletesImmediatelyOnOk to capture exceptions from worker thread
• Refactor testEventWithoutEoseTimesOut to capture exceptions from worker thread
• Add proper exception propagation mechanism using AtomicReference<Throwable>
• Ensure all assertions are checked in the main test thread after worker completes
• Verify all tests pass with the new implementation

Approach

Instead of throwing RuntimeException in the worker threads, we'll:

1. Use AtomicReference<Throwable> to capture any exceptions from the worker thread
2. After join(), check if an exception was captured and rethrow it in the main thread
3. Move assertions to the main thread where possible, or properly propagate them

This ensures that if send() blocks indefinitely, times out unexpectedly, or returns incorrect results, the test will properly fail.

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