Package src/speed_calc with the decorator, fast_function, slow_function,
constants.py and runnable lecture steps; pytest tests with a fake clock;
four screenshots rendered from real output; README lecture steps; review
record RC-007.
Task: MIL-002#1
Task: MIL-002#2
Task: MIL-002#3
Task: MIL-002#4
Task: MIL-002#5
Task: MIL-002#6
Task: MIL-002#7
