fix(cli): reject arguments to plugin list

[iamrajatrana]

Summary

Reject unexpected positional arguments passed to ossie plugin list instead of silently ignoring them and returning success. Adds table-driven coverage for zero, one, and multiple arguments.

Before

$ ossie plugin list unexpected
no plugins installed
$ echo $?
0

Unexpected arguments were silently ignored.

After

$ ossie plugin list unexpected
Error: unknown command "unexpected" for "ossie plugin list"
$ echo $?
1

Unexpected arguments are rejected with a non-zero exit code.

Related Issues

Closes #334

Tests

• go test ./...
• go vet ./...
• go build ./...
• Black-box verification that ossie plugin list unexpected exits with status 1

Checklist

• New behavior is covered by tests
• All existing CLI tests pass
• ASF license header is present on the new test file
• No third-party dependencies were added