Add computed driving flag to all relationship queries (list_relationships,
get_predecessors, get_successors). A relationship is marked as driving when
the predecessor's early end date plus lag determines the successor's early
start date.
Changes:
- Add early_start_date and early_end_date columns to activities schema
- Parse early dates from TASK table in XER files
- Implement is_driving_relationship() helper with 24hr tolerance for
calendar gaps
- Update all relationship queries to compute and return driving flag
- Add contract and unit tests for driving flag functionality
- Update spec, contracts, and documentation
Bill Ballou
af8cdc1d31