Logging a meal now opens the dialog (like weigh-ins) with an optional
Amount (g) field; existing meals can get an amount via the edit dialog,
where clearing the field drops it. The overview's Meals tile shows the
day's total grams, and the weekly card gains a Food (grams) chart with
a self-scaling axis that stays hidden until any meal has an amount.
Events carry a new grams field (REAL column, auto-migrated); addEvent's
growing optional parameters are folded into an options object.