docs: validate n8n import dry run

[Jdelg718]

Summary

• add Phase 12 n8n import/dry-run validation guide and sample approved-action bundle
• add static n8n workflow export validator
• fix n8n workflow exports for real n8n 2.18.5 import/run quirks: explicit ids, allowed file path, binary JSON parsing
• document successful sample-only dry-run on n8n-vps and cleanup

Test Plan

• 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
• imported both workflows inactive/manual on n8n-vps
• executed approved-action bridge sample-only dry-run with provider_execution:not_performed
• cleaned validation workflows/executions/temp files from n8n-vps

Safety

• no OAuth work
• no provider credentials
• no Gmail/Microsoft/IMAP/SMTP mutation actions
• dry-run/sample-only validation