feat(agenda): Epic 1 - Calendar views with FullCalendar

- E1.S1: FullCalendar setup with React wrapper
- E1.S2: Day view (timeGridDay) with hourly slots
- E1.S3: Week view (timeGridWeek) with 7-day grid
- E1.S4: Workweek view (timeGridWorkWeek, Mon-Fri)

Features:
- View switcher toolbar (Dag/Week/Werkweek)
- Date navigation (prev/next/today)
- Dutch localization (nl)
- Business hours highlighting (08:00-18:00)
- Color-coded appointments by type
- Drag-and-drop rescheduling support
- Server actions for encounter CRUD

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/epd/agenda/actions.ts

@@ -0,0 +1,182 @@
+'use server';
+
+/**
+ * Agenda Server Actions
+ *
+ * Server-side data fetching and mutations for the agenda module.
+ */
+
+import { createClient } from '@/lib/auth/server';
+import { revalidatePath } from 'next/cache';
+import type { CalendarEvent, AppointmentTypeCode, APPOINTMENT_TYPE_COLORS } from './types';
+
+const TYPE_COLORS: Record<string, { bg: string; border: string; text: string }> = {
+  intake: { bg: '#dbeafe', border: '#3b82f6', text: '#1e40af' },
+  behandeling: { bg: '#dcfce7', border: '#22c55e', text: '#166534' },
+  'follow-up': { bg: '#f3e8ff', border: '#a855f7', text: '#6b21a8' },
+  telefonisch: { bg: '#fef3c7', border: '#f59e0b', text: '#92400e' },
+  huisbezoek: { bg: '#ffedd5', border: '#f97316', text: '#9a3412' },
+  online: { bg: '#e0e7ff', border: '#6366f1', text: '#3730a3' },
+  crisis: { bg: '#fee2e2', border: '#ef4444', text: '#991b1b' },
+  overig: { bg: '#f1f5f9', border: '#64748b', text: '#334155' },
+};
+
+interface GetEncountersParams {
+  startDate: string;
+  endDate: string;
+  practitionerId?: string;
+}
+
+export async function getEncounters({
+  startDate,
+  endDate,
+  practitionerId,
+}: GetEncountersParams): Promise<CalendarEvent[]> {
+  const supabase = await createClient();
+
+  let query = supabase
+    .from('encounters')
+    .select(`
+      *,
+      patients:patient_id (
+        id,
+        name_family,
+        name_given,
+        birth_date
+      )
+    `)
+    .gte('period_start', startDate)
+    .lte('period_start', endDate)
+    .neq('status', 'cancelled')
+    .order('period_start', { ascending: true });
+
+  if (practitionerId) {
+    query = query.eq('practitioner_id', practitionerId);
+  }
+
+  const { data, error } = await query;
+
+  if (error) {
+    console.error('Error fetching encounters:', error);
+    return [];
+  }
+
+  return (data || []).map((encounter) => {
+    const patient = encounter.patients as {
+      id: string;
+      name_family: string;
+      name_given: string[];
+      birth_date: string;
+    } | null;
+
+    const patientName = patient
+      ? `${patient.name_given?.[0] || ''} ${patient.name_family}`.trim()
+      : 'Onbekende patiënt';
+
+    const typeCode = encounter.type_code as AppointmentTypeCode;
+    const colors = TYPE_COLORS[typeCode] || TYPE_COLORS.overig;
+
+    return {
+      id: encounter.id,
+      title: patientName,
+      start: encounter.period_start,
+      end: encounter.period_end || undefined,
+      backgroundColor: colors.bg,
+      borderColor: colors.border,
+      textColor: colors.text,
+      extendedProps: {
+        encounter,
+        patient: patient || undefined,
+      },
+    } as CalendarEvent;
+  });
+}
+
+interface CreateEncounterParams {
+  patientId: string;
+  practitionerId: string;
+  periodStart: string;
+  periodEnd?: string;
+  typeCode: string;
+  typeDisplay: string;
+  classCode: string;
+  classDisplay: string;
+  notes?: string;
+}
+
+export async function createEncounter(params: CreateEncounterParams) {
+  const supabase = await createClient();
+
+  const { data, error } = await supabase
+    .from('encounters')
+    .insert({
+      patient_id: params.patientId,
+      practitioner_id: params.practitionerId,
+      period_start: params.periodStart,
+      period_end: params.periodEnd,
+      type_code: params.typeCode,
+      type_display: params.typeDisplay,
+      class_code: params.classCode,
+      class_display: params.classDisplay,
+      notes: params.notes,
+      status: 'planned',
+    })
+    .select()
+    .single();
+
+  if (error) {
+    console.error('Error creating encounter:', error);
+    return { success: false, error: error.message };
+  }
+
+  revalidatePath('/epd/agenda');
+  return { success: true, data };
+}
+
+export async function updateEncounter(
+  encounterId: string,
+  updates: {
+    periodStart?: string;
+    periodEnd?: string;
+    status?: string;
+    notes?: string;
+  }
+) {
+  const supabase = await createClient();
+
+  const updateData: Record<string, unknown> = {};
+  if (updates.periodStart) updateData.period_start = updates.periodStart;
+  if (updates.periodEnd) updateData.period_end = updates.periodEnd;
+  if (updates.status) updateData.status = updates.status;
+  if (updates.notes !== undefined) updateData.notes = updates.notes;
+
+  const { data, error } = await supabase
+    .from('encounters')
+    .update(updateData)
+    .eq('id', encounterId)
+    .select()
+    .single();
+
+  if (error) {
+    console.error('Error updating encounter:', error);
+    return { success: false, error: error.message };
+  }
+
+  revalidatePath('/epd/agenda');
+  return { success: true, data };
+}
+
+export async function cancelEncounter(encounterId: string) {
+  return updateEncounter(encounterId, { status: 'cancelled' });
+}
+
+export async function rescheduleEncounter(
+  encounterId: string,
+  newStart: string,
+  newEnd: string | null
+) {
+  return updateEncounter(encounterId, {
+    periodStart: newStart,
+    periodEnd: newEnd || undefined,
+  });
+}