Per-host personalities land on iOS; goal editing in composer

New features

• Added per-host personality settings with Friendly and Pragmatic options.
• Added support for editing goals directly in the composer.
• Added a link from forked conversations back to the original thread.

Improvements and bug fixes

• Improved side chat visibility with separate conversations above the composer.
• Improved composer autocomplete for commands, skills, and plugins from any prefix.
• Improved progress visibility for subagents, tasks, and worktree creation.
• Fixed long threads loading.
• Improved workspace file search, code review drafts, steering, and host setup and recovery.
• Fixed Face ID unlocking, stopping responses, collapsed sections, and dark-mode host indicators.