fix: redact stdio command args in info

[haosenwang1018]

Summary

• redact stdio server args in mcp-cli info output
• keep the executable name visible while hiding the full argument list
• add output-format regression tests for both arg and no-arg stdio servers

Problem

Issue #217 reports that mcp-cli info can reveal secret-bearing command details. The existing info output still printed the entire stdio command line, including raw args.

Fix

formatServerDetails() now renders stdio commands as <executable> (<N> hidden arguments) instead of echoing the full arg list. This preserves useful context without leaking flags, paths, or tokens embedded in args.

Fixes #217

Validation

• bun test tests/output.test.ts
• npx tsc --noEmit
• npx @biomejs/biome check src/output.ts tests/output.test.ts
• git diff --check