Reflection follow-up: rewrite missing substrate file pr-safe-close.sh

Missing path: ~/shared-knowledge/scripts/pr-safe-close.sh Referenced in: PR-DEDUP-PROTOCOL.md lines 4,24,56,89,114,179. Presumed contents: Shell script that enforces the PR dedup-close preconditions before allowing a gh pr close. Checks: (1) you authored the PR, (2) no approved/changes-requested review decision, (3) no open human reviewer requests (bot reviewers filtered by BOT_PRED), (4) --reason flag required. Writes a JSONL row to $PR_SAFE_CLOSE_LOG (default ~/openclaw/logs/pr-safe-close.jsonl). Supports --dry-run flag. PR-DEDUP-PROTOCOL.md is the canonical spec. This is a key safety control; agents must route all gh pr close through this script.