Add maintenance intervals configuration to track maintenance by kilometers
driven. When a maintenance is marked COMPLETED, automatically calculate and
schedule the next maintenance based on interval + current odometer reading.
Features:
- MaintenanceInterval entity: stores KM/day intervals per vehicle & type
- scheduleNextMaintenance(): creates next SCHEDULED item after completion
- nextDueKm field: tracks when next maintenance is due (in kilometers)
- getDueBoard() queries already support KM-based tracking
Maintenance now "marches forward" based on distance driven, not just dates.
Each vehicle type can have different intervals (e.g., oil every 10k km, tires 50k km).
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
Added assertCapacity() checks before saving (matches single receive)
Added applyCapacityDelta() after save to increment counters
Now validates warehouse → yard → zone capacity hierarchy
Single receive already had both checks; bulk receive was gap.
