Blockchain Node:
- Replace /blocks (pagination) with /blocks-range (height range query)
- Add start/end height parameters with 1000-block max range validation
- Return blocks in ascending height order instead of descending
- Update metrics names (rpc_get_blocks_range_*)
- Remove total count from response (return start/end/count instead)
Coordinator API:
- Add effective_url property to DatabaseConfig (SQLite/PostgreSQL defaults
