Wire DMC tracker attachment into Homeboy

[chubes4]

Summary

• negotiate DMC tracker attachment capability before advertising paired Homeboy commands
• adapt read-only preview and authorized apply results to the generic Homeboy attachment envelope
• preserve exact provider failures and older-version compatibility without half-configured commands
• cover preview, apply, idempotence, resolve, and error forwarding in the provider integration fixture

Closes #448.

Depends on Extra-Chill/data-machine-code#1221 and Extra-Chill/homeboy#13427.

Verification

• bash tests/homeboy-dmc-provider.sh
• complete shell suite was exercised; unrelated existing Kimaki/service migration fixtures failed outside changed paths
• diff checks

AI assistance

OpenAI GPT-5.6 Sol via OpenCode reviewed the independent DMC and Homeboy contracts, implemented capability negotiation and DMC-specific adaptation in wp-coding-agents, added integration coverage, and ran verification. Chris Huber directed the integration and remains responsible.