feat(python-client): send bearer token on WS upgrade

[sridhar-3009]

Fixes #1395.

Problem

SensingClient (python/wifi_densepose/client/ws.py) had no credential path at all — git grep -n "Authorization\|RUVIEW_API_TOKEN" python/ returned nothing. Against a sensing-server with RUVIEW_API_TOKEN set, the Python client simply cannot connect. The TS MCP client (tools/ruview-mcp/src/http.ts) has honoured this token for a while, so this was a gap between the two clients rather than a missing feature overall.

Fix

• SensingClient.__init__ accepts a token keyword, defaulting to RUVIEW_API_TOKEN when not passed explicitly.
• When a token is present, __aenter__ sends Authorization: Bearer <token> on the WS upgrade. Python isn't browser-constrained the way the web UI is, so this goes straight on the upgrade request — no ticket/round-trip indirection, per the issue's explicit guidance.
• Handled the websockets>=12.0 keyword rename deliberately, per the issue's callout: the header kwarg to websockets.connect() is extra_headers below version 14 and additional_headers from 14 onward. Detected via inspect.signature(websockets.connect).parameters at import time, not by parsing __version__ — so it can't be thrown off by a version-string format change on either side of the cutover.

Testing

I didn't just trust the issue's description of the version split — I installed websockets 12.0, 13.1, and 16.1.1 in three isolated venvs and inspected the actual connect() signature in each to confirm exactly where extra_headers becomes additional_headers before writing the branch logic.

Added three tests to test_client_ws.py using the same in-process websockets.serve() pattern the file already uses:

• token passed to the constructor arrives as the correct Authorization: Bearer <token> header
• no token passed and RUVIEW_API_TOKEN unset → no Authorization header sent at all (not an empty one)
• RUVIEW_API_TOKEN env var is honoured when no token is passed explicitly

Ran the full test_client_ws.py suite (9 tests, including the 3 new ones) against both websockets 13.1 and 16.1.1 in separate venvs — all pass on both sides of the keyword rename. Also confirmed the change doesn't newly break ruff check beyond one pre-existing style debt already present in this file (Optional[X] vs X | None) that I matched rather than mixed styles.

[PrinceAudre]

Heads-up: #1400 and #1396 implement the same feature — bearer-token auth on the SensingClient WebSocket upgrade — editing the same lines of python/wifi_densepose/client/ws.py and python/tests/test_client_ws.py (both close #1395). So only one can merge; the other will conflict.

Both look sound. This one (#1400) fits the file's existing Optional[...] style and resolves the additional_headers/extra_headers kwarg once at import; #1396 adds a dedicated unit test for that version-split branch. Either is a fine choice — just pick one and close the other.