ui(chat): show skill names on tool cards and render sandbox file lists

[lyingbug]

Summary

• Quote the skill name (and file path when present) on read_skill / execute_skill_script stream titles so skill steps are distinguishable.
• Add dedicated result cards for read_skill (description, bundled files, instructions/content) and list_sandbox_files (path, size, mtime) instead of falling through to raw output.
• Localize the sandbox file tools and give them matching stream icons.

Test plan

• Start an agent turn that calls read_skill and confirm the step title is 读取技能：「<skill>」 (or skill/file when a file is read); expand the card and check description, file list, and content.
• Run execute_skill_script and confirm the title includes 「<skill>」 plus the script command.
• Call list_sandbox_files after a skill writes artifacts; expand the card and confirm a file list with sizes instead of raw output, including the empty-state when the directory is empty.
• Reload the session and confirm the same cards still render from history.