feat: add centralized error logging system

- Implemented Error Log API to capture and store error logs from various services.
- Updated admin_ui to include Error Log Viewer component for inspecting logs.
- Enhanced error handling in auth_api, employee_api, and transit_api to report errors to the Error Log API.
- Modified existing services to utilize the new error logging functionality.
- Updated Docker Compose configuration to include the Error Log API service.
- Added error logging service in bus_terminal for Flutter application.

admin_ui/src/components/BusLinesManager.jsx

@@ -11,7 +11,7 @@ export default function BusLinesManager({ token, user }) {
   const [estimatedDurationMinutes, setEstimatedDurationMinutes] = useState('')
   const [description, setDescription] = useState('')
   const [message, setMessage] = useState(null)
-  const [isAdmin] = useState(Boolean(user?.userCode))
+  const [isAdmin] = useState(Boolean(user?.isAdmin))
   const [deleteConfirm, setDeleteConfirm] = useState(null)
   const [editingLine, setEditingLine] = useState(null)
 

admin_ui/src/components/ErrorLogViewer.jsx

@@ -0,0 +1,74 @@
+import React, { useEffect, useMemo, useState } from 'react'
+import { errorLogClient } from '../api'
+
+const formatDate = (value) => {
+  if (!value) return '—'
+  try {
+    return new Date(value).toLocaleString()
+  } catch (_) {
+    return String(value)
+  }
+}
+
+export default function ErrorLogViewer({ token }) {
+  const client = useMemo(() => errorLogClient(token), [token])
+  const [logs, setLogs] = useState([])
+  const [service, setService] = useState('')
+  const [partOfService, setPartOfService] = useState('')
+  const [loading, setLoading] = useState(false)
+  const [message, setMessage] = useState(null)
+
+  const loadLogs = async () => {
+    setLoading(true)
+    setMessage(null)
+    try {
+      const params = { limit: 100 }
+      if (service) params.service = service
+      if (partOfService) params.partOfService = partOfService
+      const res = await client.get('/error_log', { params })
+      setLogs(res.data.errors || [])
+    } catch (err) {
+      setMessage(err.response?.data?.error || err.message || 'Kon fouten niet laden')
+    } finally {
+      setLoading(false)
+    }
+  }
+
+  useEffect(() => {
+    loadLogs()
+  }, [service, partOfService])
+
+  return (
+    <section className="card">
+      <div className="section-header">
+        <div>
+          <h2>Error log</h2>
+          <p>Laatste foutmeldingen uit de centrale logging service.</p>
+        </div>
+        <button className="secondary" onClick={loadLogs} disabled={loading}>
+          {loading ? 'Laden...' : 'Ververs'}
+        </button>
+      </div>
+
+      <div className="form-row">
+        <input placeholder="Service filter" value={service} onChange={e => setService(e.target.value)} />
+        <input placeholder="Part of service filter" value={partOfService} onChange={e => setPartOfService(e.target.value)} />
+      </div>
+
+      {message && <div className="message">{message}</div>}
+
+      <div className="list-grid">
+        {logs.map(log => (
+          <article className="mini-card" key={log.id}>
+            <strong>{log.service}</strong>
+            <div>{formatDate(log.date)}</div>
+            <div className="muted" style={{ marginTop: 6 }}>{log.partOfService || '—'}</div>
+            <div style={{ marginTop: 8 }}>{log.error}</div>
+          </article>
+        ))}
+      </div>
+
+      {!logs.length && !message && <div className="muted">Nog geen foutmeldingen gevonden.</div>}
+    </section>
+  )
+}

admin_ui/src/components/FixedScheduleEditor.jsx

@@ -172,7 +172,7 @@ const FixedScheduleEditor = ({
   const [availableDrivers, setAvailableDrivers] = useState([])
   const [pendingBatchData, setPendingBatchData] = useState(null)
 
-  const isAdmin = Boolean(user?.userCode)
+  const isAdmin = Boolean(user?.isAdmin)
 
   const resetForm = () => {
     setEditingScheduleId(null)

admin_ui/src/components/FleetManager.jsx

@@ -9,7 +9,7 @@ export default function FleetManager({ token, user }) {
   const [licensePlate, setLicensePlate] = useState('')
   const [message, setMessage] = useState(null)
   const [canCreateBus, setCanCreateBus] = useState(true)
-  const [isAdmin] = useState(Boolean(user?.userCode))
+  const [isAdmin] = useState(Boolean(user?.isAdmin))
   const [editingBus, setEditingBus] = useState(null)
   const [deleteConfirm, setDeleteConfirm] = useState(null)
 

admin_ui/src/components/LinkStop.jsx

@@ -13,7 +13,7 @@ export default function LinkStop({ token, user }) {
   const [draggedItem, setDraggedItem] = useState(null)
   const [deleteConfirm, setDeleteConfirm] = useState(null)
 
-  const isAdmin = Boolean(user?.userCode)
+  const isAdmin = Boolean(user?.isAdmin)
 
   const nextOrder = useMemo(() => stops.length + 1, [stops])
 

admin_ui/src/components/ScheduleMaker.jsx

@@ -11,7 +11,7 @@ export default function ScheduleMaker({ token, user }) {
   const [drivers, setDrivers] = useState([])
   const [selectedDriverFilter, setSelectedDriverFilter] = useState('')
   const [message, setMessage] = useState(null)
-  const [isAdmin] = useState(Boolean(user?.userCode))
+  const [isAdmin] = useState(Boolean(user?.isAdmin))
   const [overviewDate, setOverviewDate] = useState(new Date().toISOString().split('T')[0])
 
   const loadScheduleTemplates = async () => {

admin_ui/src/components/StopsManager.jsx

@@ -8,7 +8,7 @@ export default function StopsManager({ token, user }) {
   const [lat, setLat] = useState('')
   const [lon, setLon] = useState('')
   const [message, setMessage] = useState(null)
-  const [isAdmin] = useState(Boolean(user?.userCode))
+  const [isAdmin] = useState(Boolean(user?.isAdmin))
   const [deleteConfirm, setDeleteConfirm] = useState(null)
   const [editingStop, setEditingStop] = useState(null)