Add switcher-claude multi-account support with profile selector in AgentPane
toolbar, skill autocomplete menu (type / in prompt), and 5 new AgentQueryOptions
fields (setting_sources, system_prompt, model, claude_config_dir,
additional_directories) flowing through full stack from Rust to SDK.
New Tauri commands: claude_list_profiles, claude_list_skills, claude_read_skill,
pick_directory. New frontend adapter: claude-bridge.ts.
ff49e7e176