websocket: make the output dial honour its context

[Leward]

The output dial takes a context and discards it. A peer that accepts TCP and then stays silent keeps Connect blocked until the dialer handshake timeout of 45s, which blocks a graceful shutdown for that whole time.

Replace the dial with dialContext, which the input already uses. The tls and non-tls paths now differ only by the dialer field they set, so the duplicated dial call goes away.

Connect and ConnectionTest both pass a real context, and the async writer gives Connect a soft stop context. A dial to a silent peer now ends with the context error instead of running to the handshake timeout.

Add a test mirroring the input test, using the shared listener helpers so it only adds the writer constructors.

Refs:

• CON-545
• VM-75

[claude]

Commits

LGTM

Review

Small, well-scoped fix: websocketWriter.dial now routes through the shared dialContext helper instead of dialer.Dial, so the output honours its context during both the TCP/TLS handshake and the websocket upgrade exchange. The TLS and non-TLS branches collapse to a single dial call that differs only in which dialer field is set, matching the shape already used by websocketReader.getConn. Connect and ConnectionTest both forward a real context, and the added table-driven test mirrors the input test exactly (cancelled-before-dial, cancelled-mid-handshake, deadline-exceeded-mid-handshake), reusing the existing newHangingListener / newUnreachableAddr / awaitWithin / requireAccepted helpers rather than duplicating them. The CHANGELOG entry is correctly widened from Input to Input/Output.

Checked and found clean: the context-error path in dialContext closes any conn it produced before returning, so Connect cannot cache a live client after a context error; the deferred res.Body.Close() still runs on that path; ConnectionTest only touches conn when err is nil; and no goroutine or listener introduced by the test helpers outlives the subtest.

LGTM

[claude]

Commits
LGTM

Review
Small, focused change: the output 'websocket' dial now routes through the shared dialContext helper instead of dialer.Dial, so a peer that accepts TCP and then goes silent no longer pins shutdown to the 45s handshake timeout. The dial body is now identical to the input reader's, and the new test mirrors TestWebsocketConnectContextDone while reusing the existing listener helpers. Connect still closes the upgrade response body via defer, and dialContext closes any connection it returns on the context-error path, so no new leaks. CHANGELOG entry correctly widened to cover both components.

LGTM