feat: sync generic context capabilities

[eddiearc]

Summary

• add generic task-board title and note-removal lifecycle commands with atomic invariant protection
• make plan-go rendered guidance shell-safe and test literal output
• include the finite Claude compatibility self-check closure in fresh initialization
• ignore local Playwright MCP cache material

Validation

• scripts/check-all.sh --skip-secrets
• direct temporary-board CLI lifecycle and loop-spec probes
• git diff --check

check-secrets.sh was attempted twice but is unavailable locally because the repository pins Gitleaks v8.24.2 and this machine has v8.30.0.