Add performance goals to all 34 metcons with calculation methodology

Every metcon now has a goal object with target and scaleDown fields.
Goals serve as level validation: if you hit the target, your level is
correct. If you miss it, drop one level next time.

Calculated from movement speeds, transition times, and fatigue factors.
Full methodology documented in spec/programming.md.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: OneMuppet