Feature A of 2: lets a plan cell hold up to 3 records (additive
assignments + day exceptions) via the layered entries/overrides model,
no migration. resolveCell/resolveGrid return arrays; cap enforced per
layer on create; grid shows up to 3 stacked; cell editor becomes a
day panel; dashboard today-card shows up to 3. Feature B (bulk create)
decisions captured as deferred.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
628cd54a81