fix(vscode): run the file, not a test name, from the Run Test commands

[pbertsch]

Summary

• The VS Code extension passed --name <test> to probe test in four places: the Run Test at Cursor command, the CodeLens buttons (run, per-session run and debug), and the Tests view. This version of the CLI defines no such flag, so each of those runs failed with an unknown-flag error.
• The fix removes the flag, so those commands run the file that holds the test. "FlutterProbe: Run Test File at Cursor" keeps its command id, so the Ctrl+Shift+T binding still works. The CodeLens titles and tooltips, and the docs, say that a run covers the file. The CLI is not changed, and no flag is added.
• A node test reads the extension's sources and fails if any of them passes --name again. It skips itself, because it names the flag.
• A changelog entry goes under Unreleased → Fixed.

Test plan

• npm test in vscode/: compile, then 25 node:test tests, including the new guard
• Not run inside VS Code: the commands and the CodeLens buttons were compiled, not run
• Not run against a device

🤖 Generated with Claude Code