fix(permissions): deny safe-read auto-approval for shell redirections

[SeashoreShi]

Summary

• deny safe-read auto-approval for shell segments that contain shell redirection operators
• keep the existing safe-read allowlist intact for true read-only commands
• add regression tests covering >, >>, and heredoc redirections while preserving quoted / escaped literals

Why

checkShellCommand() currently auto-approves commands when every parsed segment matches a safe-read pattern like cat *. That still treats commands such as cat README.md > variant.txt as read-only even though the execution path later runs the original command with shell: true, letting the shell perform a write redirection.

This change keeps the current permission model but prevents safe-read auto-approval whenever a segment contains unquoted redirection syntax.

Testing

• npm test -- src/capabilities/permissions.test.ts
• npm run typecheck