chore(docs): Refactor PATTERNS.md and DISCOVERIES.md with automated cleanup (#1670)

## Summary
- Reduce DISCOVERIES.md from 2321 to 321 lines (86% reduction)
- Create DISCOVERIES_ARCHIVE.md for historical entries
- Add Cross-Domain Pattern Applicability Analysis to PATTERNS.md
- Add weekly GitHub Actions workflow for automated documentation cleanup

## Changes
- **DISCOVERIES.md**: Condensed to active entries only (Oct-Nov 2025)
- **DISCOVERIES_ARCHIVE.md**: New archive file with 9 historical entries
- **PATTERNS.md**: Added Decision-Making Patterns section
- **docs-weekly-cleanup.yml**: Weekly workflow using Claude for automated curation
- **docs_cleanup.py**: Python script for Claude-powered cleanup
- **.pre-commit-config.yaml**: Exclude .github/scripts from pyright/imports checks

Fixes #1669

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Ubuntu <azureuser@amplihack2.yb0a3bvkdghunmsjr4s3fnfhra.phxx.internal.cloudapp.net>
Co-authored-by: Claude <noreply@anthropic.com>

Author: 3 people