Use --target_name as the WebSocket generator uri - #2315

Fixes #2314.

--target_name reaches the WebSocket generator as the name option (garak/cli.py:660-663), but WebSocketGenerator.__init__ only read the uri from its uri argument or option, so it kept the default wss://echo.websocket.org. A run against ws://localhost:3000/chat sent every prompt to the public echo server and scored the echoes. The docs say the uri "can also be passed with --target_name" (docs/source/generators/websocket.rst:13).

Now, when no uri was passed or configured and name is a ws:// or wss:// URL, it is used as the uri. An explicitly configured uri still wins, and with nothing set the echo default is unchanged (test_init_no_uri).

Why this isn't a tiny one-off PR

It changes which server garak talks to, so whether a WebSocket scan tests the target at all. That's a behaviour fix for a documented CLI option, with tests (AGENTS.md:54).

Not a duplicate

gh issue list / gh pr list --repo nvidia/garak --state all for "websocket target_name", "websocket uri", "WebSocketGenerator" and "echo.websocket.org": no issue or PR covers this. #2263 is a different WebSocket bug (empty outputs after the first prompt). #1589 changes cli.py but not the target name handling.

Tests

python -m pytest tests/generators/test_websocket.py tests/generators/test_generators.py
142 passed
python -m pytest tests/generators/
457 passed, 17 skipped

test_init_target_name_sets_uri covers both config shapes the CLI writes (generators.websocket.name and generators.websocket.WebSocketGenerator.name) and fails on main; test_init_configured_uri_wins_over_name pins the explicit uri. black --check is clean.

AI tools helped write this change and the tests. I reviewed every changed line and ran the tests above myself.