Summary

Implement the CalendarStrategy for the pluggable ceremony scheduling system.

Traditional time-based scheduling using MeetingFrequency intervals. Ceremonies fire on a wall-clock cadence regardless of task progress.

Design Reference

See Ceremony Scheduling design page -- "Calendar" strategy section.

Key Behaviors

• should_fire_ceremony: delegates to MeetingFrequency-based interval checking
• should_transition_sprint: returns IN_REVIEW at duration_days boundary; task completion does NOT trigger transition
• All lifecycle hooks: no-op (stateless strategy)
• Default velocity calculator: CalendarVelocityCalculator (pts/day)

Implementation

• New: src/synthorg/engine/workflow/strategies/calendar.py
• New: tests/unit/engine/workflow/strategies/test_calendar.py
• Implement CeremonySchedulingStrategy protocol from feat: sprint ceremony runtime scheduler with task-driven cadence support #961

Also implement: CalendarVelocityCalculator

• New: src/synthorg/engine/workflow/velocity_calculators/calendar.py
• New: tests/unit/engine/workflow/velocity_calculators/test_calendar.py
• Primary unit: pts/day

Dependencies

• feat: sprint ceremony runtime scheduler with task-driven cadence support #961 (protocol interfaces + reference implementation)