Add recurring series to events

A Series checkbox under When opens a panel for the schedule:
weekly on chosen weekdays, monthly by date, or monthly by weekday
position, every N weeks or months, with meeting times and an
optional meeting count. starts_on anchors the schedule and ends_on
bounds it, so effective_status needs no change.

Occurrences are derived, not stored. src/lib/eventSeries.ts builds
the schedule label shown on cards and the event page, and the
upcoming dates listed on the event page.

Migration 016 adds the columns; the CRUD engine gains a time type.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/components/admin/fields.tsx

@@ -225,7 +225,9 @@ export function Field({ field, value, row, options, error, onChange }: FieldProp
           </div>
         ) : (
           <input
-            type={widget === "number" ? "number" : widget === "date" ? "date" : "text"}
+            type={
+              widget === "number" || widget === "date" || widget === "time" ? widget : "text"
+            }
             step={widget === "number" ? "any" : undefined}
             {...common}
             readOnly={locked}