feat: opportunity list — date-range filter + expose appointmentDate/Time for calendar view

[nadavosa]

Context

Linked to need4deed-org/fe#646 — the calendar page needs to fetch dated, non-accompanying opportunities for a given month.

What's needed

1. New query params on GET /opportunity

Param	Type	Description
`appointmentDateFrom`	ISO date string	Filter opps with appointmentDate ≥ this date
`appointmentDateTo`	ISO date string	Filter opps with appointmentDate ≤ this date
`hasAppointmentDate`	boolean	When true, return only opps where appointmentDate is not null
`excludeAccompanying`	boolean	When true, exclude accompanying volunteerType

The FE will call with the start and end of the visible calendar month, e.g.:
`GET /opportunity?appointmentDateFrom=2026-06-01&appointmentDateTo=2026-06-30&hasAppointmentDate=true&excludeAccompanying=true`

2. Include appointmentDate and appointmentTime in the list response

Currently the opportunity list DTO (`dtoOpportunityGetList`) may not include `appointmentDate` / `appointmentTime`. These fields must be present in the list response so the FE can pin events on the correct calendar day without fetching each opportunity individually.

Add to list response per opportunity:

• `appointmentDate` (ISO string or null)
• `appointmentTime` (string or null)
• `agentTitle` (the agent/center name — for the day-click panel on the FE)

3. SDK

Update `ApiOpportunityGetList` in the SDK to include the three fields above if not already present.

Tasks

• Add `appointmentDateFrom`, `appointmentDateTo`, `hasAppointmentDate`, `excludeAccompanying` to `opportunityListQuerySchema`
• Apply filters in the opportunity list handler
• Expose `appointmentDate`, `appointmentTime`, `agentTitle` in `dtoOpportunityGetList`
• Update SDK type `ApiOpportunityGetList`