test: Reqnroll BDD acceptance suite for the CLI (PROT-41)

[BlakeHastings]

What

Adds a black-box acceptance test suite that drives the real built protostar binary the way a user runs it, plus the CI to run it on every PR.

Resolves PROT-41.

test/Protostar.Cli.Acceptance/

• Reqnroll (the maintained successor to SpecFlow) + xUnit, with CliWrap executing the compiled binary as a child process and asserting on stdout/stderr, exit code, and filesystem side effects. No mocking of the command layer.
• Features/*.feature — 5 Gherkin specs: --version, default command, --help, install, uninstall.
• Steps/CliSteps.cs — bindings using Cucumber expressions.
• Support/CliRunner.cs — locates the binary via PROTOSTAR_BIN or a repo-root walk.
• Support/Sandbox.cs — a throwaway temp dir per scenario. Install/uninstall pass --no-modify-path, so the suite never edits the machine PATH.

feat(cli): --no-modify-path on uninstall

Uninstall previously rewrote the Windows user PATH unconditionally, which made it unsafe to run under test. The flag mirrors install and guards the PATH edit. Committed separately so release-please sees a clean feature.

CI (.github/workflows/ci.yml)

• Triggers on pull_request and pushes to main.
• Matrix across ubuntu-latest and windows-latest (exercises the OS-specific binary name and install paths).
• dotnet build -c Release then dotnet test -c Release. Actions pinned to SHAs per PROT-39.

Verification

• dotnet build -c Release: 0 warnings, 0 errors.
• dotnet test -c Release: 7/7 scenarios pass locally (~1s).

Note on scope

The "already installed" idempotency branch only fires when the running exe equals the destination, which a black-box test using the framework-dependent build cannot reach (a copied single exe cannot self-run). The re-install scenario instead asserts a second install is safe and the binary is present. Once CI publishes a self-contained binary, that path becomes testable.

[ljones491]

Is CliWrap running our installed CLI? So if we want to write BDD tests about our configuration, will the tests change our settings?

[BlakeHastings]

Is CliWrap running our installed CLI? So if we want to write BDD tests about our configuration, will the tests change our settings?

It is running our CLI but it is sandboxed. I added the ability to provide the path to use for the configuration of protostar / other harnesses. The BDD will setup files for certain harnesses at a location and then pass that location to protostar who won't see a difference between them vs the actual installed location of something like claude.

So no we are good.