Expose a plan-bound worktree retention provider

[chubes4]

Summary

• expose studio wp datamachine-code workspace retention-provider as a strict JSON stdin/stdout endpoint
• delegate plan, apply, status, and evidence operations directly to the DB-backed CleanupRunService
• persist stable plan identity, inventory continuation, and normalized blockers with reviewed cleanup runs
• reject mismatched apply identity before mutation while preserving existing per-row safety revalidation
• return bounded Homeboy-compatible continuation, effects, blockers, and status/evidence references

Provider implementation for Extra-Chill/homeboy#13813 and Extra-Chill/homeboy#13842.

Verification

• php tests/worktree-retention-provider.php
• php tests/cleanup-run-durable-planning.php
• php -l inc/Workspace/WorktreeRetentionProvider.php
• php -l inc/Workspace/CleanupRunService.php
• php -l inc/Cli/Commands/WorkspaceCommand.php
• git diff --check

AI assistance

OpenAI gpt-5.6-sol via OpenCode inspected DMC cleanup planning and apply persistence, implemented the thin Homeboy protocol adapter, added fail-closed identity and wire-shape tests, and ran targeted verification. Chris Huber directed the architecture and reviewed the resulting behavior.