fix(lint): enable require-await rule and remove unnecessary async

Enable @typescript-eslint/require-await to flag async functions without
await. Convert synchronous functions from async to sync:
- AuthService.login() - JWT generation is synchronous
- AuthController.login() - now calls sync service method
- AlertService.sendAlert() - only uses sync logger
- MetricsPersistenceService.persistMetrics() - fire-and-forget pattern

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

features/status-dashboard/server/src/api/hosts.controller.integration.spec.ts

@@ -107,7 +107,7 @@ describe('HostsController (Integration)', () => {
     await app.init();
 
     // Generate valid JWT token for authenticated tests
-    validJwtToken = await authService.login('test-password');
+    validJwtToken = authService.login('test-password');
   });
 
   afterEach(async () => {
@@ -156,7 +156,7 @@ describe('HostsController (Integration)', () => {
 
       it('should reject request with expired JWT token', async () => {
         // Create token with immediate expiration
-        const _expiredToken = await authService.login('test-password');
+        const _expiredToken = authService.login('test-password');
         // Override token expiration by creating a new token manually
         // (in real scenario, wait for expiration or mock time)
 

features/status-dashboard/server/src/api/metrics.controller.integration.spec.ts

@@ -177,7 +177,7 @@ describe('MetricsController (Integration)', () => {
       });
 
       it('should reject JWT authentication (only mTLS/API Key allowed)', async () => {
-        const jwtToken = await authService.login('test-password');
+        const jwtToken = authService.login('test-password');
 
         await request(app.getHttpServer())
           .post('/api/metrics/report')
@@ -466,7 +466,7 @@ describe('MetricsController (Integration)', () => {
       });
 
       it('should NOT accept JWT authentication (only mTLS/API Key)', async () => {
-        const jwtToken = await authService.login('test-password');
+        const jwtToken = authService.login('test-password');
 
         await request(app.getHttpServer())
           .post('/api/metrics/report')

features/status-dashboard/server/src/api/status.controller.integration.spec.ts

@@ -116,7 +116,7 @@ describe('StatusController (Integration)', () => {
 
     await app.init();
 
-    validJwtToken = await authService.login('test-password');
+    validJwtToken = authService.login('test-password');
   });
 
   afterEach(async () => {

features/status-dashboard/server/src/auth/auth.controller.ts

@@ -39,11 +39,11 @@ export class AuthController {
   @HttpCode(HttpStatus.OK)
   @UseGuards(RateLimitGuard)
   @RateLimit({ ttl: 60, limit: 5 }) // 5 attempts per minute
-  async login(@Body() dto: LoginDto): Promise<LoginResponse> {
+  login(@Body() dto: LoginDto): LoginResponse {
     let token: string | null;
 
     try {
-      token = await this.authService.login(dto.password, dto.totp);
+      token = this.authService.login(dto.password, dto.totp);
     } catch (error) {
       // If TOTP is required but not provided, throw specific error
       if (error instanceof UnauthorizedException) {

features/status-dashboard/server/src/auth/auth.service.ts

@@ -23,7 +23,7 @@ export class AuthService {
    * @returns JWT token or null if authentication fails
    * @throws UnauthorizedException if TOTP is required but not provided
    */
-  async login(password: string, totp?: string): Promise<string | null> {
+  login(password: string, totp?: string): string | null {
     const { adminPassword, totpSecret } = this.configService.auth;
 
     // Check password

features/status-dashboard/server/src/cron/alert.service.ts

@@ -15,7 +15,7 @@ export class AlertService {
   /**
    * Send alert notification
    */
-  async sendAlert(message: string, severity: AlertSeverity = 'info'): Promise<void> {
+  sendAlert(message: string, severity: AlertSeverity = 'info'): void {
     const timestamp = new Date().toISOString();
     const severityUpper = severity.toUpperCase();
     const formattedMessage = `[${timestamp}] [${severityUpper}] ${message}`;

features/status-dashboard/server/src/logging/audit-logging.interceptor.spec.ts

@@ -8,7 +8,7 @@ describe('AuditLoggingInterceptor', () => {
   let interceptor: AuditLoggingInterceptor;
   let mockLogger: any;
 
-  beforeEach(async () => {
+  beforeEach(() => {
     interceptor = new AuditLoggingInterceptor();
     mockLogger = {
       log: vi.fn(),

features/status-dashboard/server/src/storage/metrics-persistence.service.ts

@@ -33,7 +33,7 @@ export class MetricsPersistenceService {
    *
    * @param metrics - Host metrics to persist
    */
-  async persistMetrics(metrics: HostMetrics): Promise<void> {
+  persistMetrics(metrics: HostMetrics): void {
     // Convert HostMetrics to VPSResources format
     const vpsResources = this.convertToVPSResources(metrics);