- Add docs/INDEX.md with navigable index and quick reference guides
- Add 9 knowledge base files covering project overview, Bitcoin domain,
architecture, modules, API reference, database schema, deployment/security
- Update AGENTS.md with knowledge base reference and update policy
- Add tests/sql_injection_tests.rs with regression tests for SQL injection
- Fix SQL injection vulnerabilities in bal-pusher.rs:
* Replace string-formatted UPDATE IN with loop + parameterized queries
* Replace string-formatted UPDATE push_err with parameterized query
* Add chain name validation in calculate_stats to prevent env var tampering
- Update .gitignore to exclude bal-pusher.env and bal-pusher.sh
