websocket: respect wss dial timeout

[Rememorio]

Summary

• Pass the configured websocket client timeout into WSS TLS dialing.
• Apply the same timeout to the HTTP Upgrade handshake and clear the deadline after a successful upgrade.
• Close the raw connection on failed client upgrade paths.
• Add regression tests for WSS TLS handshake timeout and websocket upgrade timeout.
• Initialize the outbound-buffer test TCP fixture so root package tests do not panic when closing it.

Compatibility

This is a bug fix for existing WithTimeout behavior. It does not add or remove public APIs.

Validation

• cd extensions/websocket && go test ./... -count=1
• go test . -run TestTCPConnWritevOutboundBufferLimitExceeded -count=1
• go test . -count=1

[WineChord]

LGTM