BashSwiftScriptTests: end-to-end verify Subprocess.run hits bash builtins

[odrobnik]

Closes the verification loop on the polyglot subprocess unification:

• Cocoanetics/ShellKit#1 — Shell.processLauncher primitive ✅ merged
• Cocoanetics/SwiftBash#19 — BashProcessLauncher resolves against the bash command registry ✅ merged
• Cocoanetics/SwiftScript#5 — import Subprocess bridge routes through Shell.current.processLauncher ✅ merged

A SwiftScript script under SwiftBash that does Subprocess.run(Executable.name(\"echo\"), ...) should not reach posix_spawn; it should hit EchoCommand (the pure-Swift bash builtin). Two tests confirm this end-to-end — they're the script-author-visible payoff for the layered work above.

Tests

subprocessRunRoutesThroughBashCommandRegistry — script:

#!/usr/bin/env swift-script
import Subprocess
let r = try await Subprocess.run(
    Executable.name(\"echo\"),
    arguments: [\"hello-from-bash-builtin\"],
    output: Output.string(limit: 4096))
if let out = r.standardOutput, r.terminationStatus.isSuccess {
    print(\"got=\\(out)\", terminator: \"\")
}

Bridge calls Shell.current.processLauncher.launch(...), BashProcessLauncher resolves \"echo\" to the registered EchoCommand, the captured standardOutput round-trips back to the script and prints got=hello-from-bash-builtin\\n. No posix_spawn, no host /bin/echo involvement.

subprocessRunWithCanonicalPathHitsBashBuiltin — same flow with Executable.path(\"/bin/echo\"). Verifies the canonical-bin-path resolution rule (PR #19's P2 fix): /bin/echo matches BinCatalog.knownPaths[\"echo\"], so the launcher dispatches to the registered builtin instead of throwing ProcessLaunchUnresolved.

Both pass locally.

Test plan

• CI green on macOS / iOS / tvOS / watchOS / Linux / Windows / Android
• Local: 2/2 e2e tests pass

🤖 Generated with Claude Code

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