feat: add persistent yolo mode setting

[alecuba16]

Summary

Adds persistent YOLO mode (auto-approve all tool calls without prompts) that survives restarts and is inherited by sub-agents.

Changes

• Settings: yoloMode: bool in settings.json, serialized as "yoloMode", merged via OR in Settings::merge()
• effective_config(): forces BypassPermissions when yolo_mode is true
• CLI: --permission-mode changed to Option<CliPermissionMode>, preserving settings value when unset; --yolo/--dangerously-skip-permissions overrides settings
• TUI: /yolo slash command toggles at runtime, persists to settings.json, updates config.permission_mode immediately
• Settings screen: YOLO mode toggle entry
• Config tool: get/set yoloMode via /config
• Sub-agents: inherit parent's permission_mode via cloned ToolContext — no extra wiring needed
• Docs: configuration.md documents yoloMode key

Test plan

• cargo test --package claurst-core -- yolo_mode — 3 tests pass
• cargo test --package claurst-tui -- test_yolo_slash_command — passes
• cargo check --workspace — clean

[alecuba16]

Closing in favor of consolidated group branches. The changes from this PR have been merged into a functional group branch.