docs: add reviewed action bridge promotion plan

[Jdelg718]

Summary

• Adds Phase 13 Reviewed Action Bridge Promotion Plan.
• Defines the safety gate before any dry-run bridge becomes live provider execution.
• Updates README, ROADMAP, HANDOFF, and n8n bridge docs to point at the Phase 13 gate.
• Adds tests proving durable audit-id dedupe, n8n-only credential ownership, dry-run default, emergency stop, sandbox/manual testing, and Rex/Gus review requirements.

Safety Boundaries

• No OAuth implementation.
• No provider credentials.
• No live Gmail/Microsoft/IMAP/SMTP mutation nodes.
• No BotFucker core live-provider behavior changes.
• Phase 13 is docs/tests only.

Verification

• python3 scripts/validate_n8n_workflow_exports.py
• python3 -m py_compile outreach_filter.py botfucker/*.py scripts/validate_n8n_workflow_exports.py
• python3 -m unittest discover -s tests -v

Team Review

• Rex: PASS — no security/spec blockers.
• Gus: APPROVED — no ops/n8n blockers.