Add mock webOS websocket adapter test harness

[Staphylococcus]

Parent: #20

Phase: 1.1.x native foundation.

Goal:
Create a reusable mock webOS websocket server so the webOS adapter can be tested without a real TV.

Scope:

• Support registration with an existing key.
• Support first-time pairing and rejected pairing responses.
• Support request/response correlation by ID, including out-of-order responses.
• Support malformed frames, timeout scenarios, and webOS error payloads.
• Make the harness reusable for future webOS input, power, screen, and brightness tests.

Acceptance criteria:

• WebOS adapter tests do not require a real TV.
• Tests can assert exact SSAP request payloads.
• Tests can prove responses are matched by request ID rather than by arrival order.
• The harness lives under the Rust test/support structure and does not affect production runtime behavior.
• The harness is webOS-specific and does not pretend to be a generic multi-brand TV emulator.

Out of scope:

• Full TV emulation.
• Samsung/Tizen or other non-webOS adapters.
• Replacing existing bscpylgtv mocks before the webOS adapter becomes production-capable.