Add shared backend for running dashboard

Align pain chart points vertically by switching to categorical LineChart

Sort runs by date within each week before assigning jitter

Sort pain chart points by date instead of x-position

Add connecting lines to pain scatter points and center legend

Show individual run pain values as jittered scatter points

Support independent per-location injury tracking

Add injury pain tracking with per-location during/after metrics

Add single run injury threshold with BJSM info tooltip

Add notes, inline editing, RPE descriptions, decimal inputs, and ACWR recommendations

Add running dashboard with weekly tracking, 10% rule recommendations, and charts