feat: add auto-mode toggle (--permission-mode auto) for Claude sessions

[DaniFdz]

Summary

Closes #440

Adds support for Claude Code's recently released auto mode (--permission-mode auto), which provides a middle ground between full interactivity and --dangerously-skip-permissions:

A classifier model reviews commands before they run, blocking scope escalation, unknown infrastructure, and hostile-content-driven actions while letting routine work proceed without prompts.

Changes

• ClaudeSettings — new auto_mode config field (toml:"auto_mode")
• ClaudeOptions — new AutoMode bool field; ToArgs() and ToArgsForFork() emit --permission-mode auto when set
• buildClaudeExtraFlags / resume command builder — instance.go updated to pass the flag when launching sessions
• Precedence: dangerous_mode > auto_mode > allow_dangerous_mode
• New Session & Fork dialogs — "Auto mode" checkbox added between Skip permissions and Chrome mode
• Setup wizard — same checkbox added to first-time setup
• Config reference — docs updated with the new key
• Tests — coverage for auto_mode in ToArgs, ToArgsForFork, and NewClaudeOptions

Config example

[claude]
dangerous_mode = false   # --dangerously-skip-permissions (bypasses all checks)
auto_mode = true         # --permission-mode auto (classifier-based auto-approval)

Screenshot