View Upcoming Appointments

# User Story

**Title:**
_As a patient, I want to view my upcoming appointments, so that I can prepare accordingly._

**Acceptance Criteria:**
1. Upcoming appointments are displayed.
2. Appointment details include doctor, date, and time.
3. Only future appointments are shown.

**Priority:** Medium

**Story Points:** 3

**Notes:**
- Appointments should be displayed in chronological order.