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.

auth_api/index.js

@@ -18,7 +18,51 @@ app.use((req, res, next) => {
   next();
 });
 
+const ERROR_LOG_API_URL = process.env.ERROR_LOG_API_URL || 'http://localhost:5003/error_log';
+
+function friendlyErrorMessage(statusCode) {
+  if (statusCode === 400) return 'Controleer je invoer en probeer opnieuw.';
+  if (statusCode === 401) return 'Je sessie is verlopen. Log opnieuw in.';
+  if (statusCode === 403) return 'Je hebt hier geen toegang toe.';
+  if (statusCode === 404) return 'Niet gevonden.';
+  return 'Er ging iets mis. Probeer het later opnieuw.';
+}
+
+async function reportError({ partOfService, error }) {
+  try {
+    await fetch(ERROR_LOG_API_URL, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({
+        service: 'auth_api',
+        partOfService,
+        error,
+      }),
+    });
+  } catch (_) {}
+}
+
+app.use((req, res, next) => {
+  const originalJson = res.json.bind(res);
+  res.json = (body) => {
+    if (res.statusCode >= 400 && body && typeof body === 'object') {
+      const rawError = body.error || body.message || body.details || `HTTP ${res.statusCode}`;
+      void reportError({ partOfService: `${req.method} ${req.originalUrl}`, error: rawError });
+      return originalJson({ error: friendlyErrorMessage(res.statusCode) });
+    }
+    return originalJson(body);
+  };
+
+  next();
+});
+
 const JWT_SECRET = process.env.JWT_SECRET;
+const ADMIN_USER_CODES = new Set(
+  String(process.env.ADMIN_USER_CODES || '')
+    .split(',')
+    .map(c => Number(c.trim()))
+    .filter(Number.isFinite)
+);
 
 
 app.post('/login', async (req, res) => {
@@ -33,13 +77,15 @@ app.post('/login', async (req, res) => {
     const ok = await bcrypt.compare(password, user.password);
     if (!ok) return res.status(401).json({ error: 'invalid_credentials' });
 
-    const payload = { userId: user.id, userCode: user.usercode };
+    const isAdmin = ADMIN_USER_CODES.has(Number(user.usercode));
+    const payload = { userId: user.id, userCode: user.usercode, isAdmin };
     const token = jwt.sign(payload, JWT_SECRET, { expiresIn: '1h' });
 
-    res.json({ token, user: { id: user.id, userCode: user.userCode, job: user.job } });
+    res.json({ token, user: { id: user.id, userCode: user.usercode, job: user.job, isAdmin } });
   } catch (err) {
+    await reportError({ partOfService: `${req.method} ${req.originalUrl}`, error: err?.stack || err?.message || String(err) });
     console.error(err);
-    res.status(500).json({ error: 'internal_error' });
+    res.status(500).json({ error: friendlyErrorMessage(500) });
   }
 });
 
@@ -51,7 +97,8 @@ app.get('/me', async (req, res) => {
     const payload = jwt.verify(token, JWT_SECRET);
     res.json({ user: payload });
   } catch (err) {
-    res.status(401).json({ error: 'invalid_token' });
+    void reportError({ partOfService: `${req.method} ${req.originalUrl}`, error: err?.stack || err?.message || String(err) });
+    res.status(401).json({ error: friendlyErrorMessage(401) });
   }
 });