fix: stabilize grounded hosted-agent certification

[w1ne]

Summary

• accept proven bounded temporal twin results without weakening oracle evidence
• make compile-recovery, partial-coverage, STM32 preservation, and unsupported-board workflows deterministic
• reject stale negative context fields in refreshed packs and sync the VS Code context engine
• fix successful certification cleanup exit

Verification

• strict five-scenario hosted run: CERTIFIED, exit 0
• develop agent oracle, JSONL, wiring, e2e, and skill contracts pass
• production context boundary deployed separately via labwired#1699

Evidence: /tmp/labwired-develop-cert-final18-20260815