fx 0.0.17 adds subagents, Token Pass

By bringing nested subagents into a 6MB native Zig binary, fx proves that multi-agent execution doesn't require heavy runtimes or bulky IDE wrappers.

• –Subagents can nest two levels deep with independent models, effort settings, and permission boundaries while remaining inspectable and steerable mid-execution
• –First-class Vercel Token Pass integration prioritizes subsidized models in the picker, reducing out-of-pocket API costs for teams
• –The unified toolbox system consolidates skills and MCP selection into static schemas, boosting prompt cache hit rates from 61.3% to 82.0%
• –Background process steering lets developers redirect agents without terminating running shell jobs or losing terminal context