Fix failing backend tests in preflight checks

Fixes three test failures that were blocking release workflow:

1. TestApplyDockerReportGeneratesUniqueIDsForCollidingHosts:
   - Initialize dockerTokenBindings and dockerMetadataStore in test helper
   - These maps were nil causing panic on first access

2. TestSendGroupedAppriseHTTP & TestSendTestNotificationAppriseHTTP:
   - Configure allowlist to permit localhost (127.0.0.1) for test servers
   - SSRF protection was blocking httptest.NewServer() URLs
   - Tests need to allowlist the test server IP to bypass security checks

Related to workflow fix in 5fa78c3e3.

internal/monitoring/monitor_docker_test.go

@@ -14,10 +14,12 @@ func newTestMonitor(t *testing.T) *Monitor {
 	t.Helper()
 
 	return &Monitor{
-		state:              models.NewState(),
-		alertManager:       alerts.NewManager(),
-		removedDockerHosts: make(map[string]time.Time),
-		rateTracker:        NewRateTracker(),
+		state:                  models.NewState(),
+		alertManager:           alerts.NewManager(),
+		removedDockerHosts:     make(map[string]time.Time),
+		rateTracker:            NewRateTracker(),
+		dockerTokenBindings:    make(map[string]string),
+		dockerMetadataStore:    config.NewDockerMetadataStore(t.TempDir()),
 	}
 }
 

internal/notifications/notifications_test.go

@@ -251,6 +251,11 @@ func TestSendGroupedAppriseHTTP(t *testing.T) {
 	}))
 	defer server.Close()
 
+	// Allow localhost for test server (SSRF protection normally blocks this)
+	if err := nm.UpdateAllowedPrivateCIDRs("127.0.0.1"); err != nil {
+		t.Fatalf("failed to configure allowlist: %v", err)
+	}
+
 	nm.SetAppriseConfig(AppriseConfig{
 		Enabled:        true,
 		Mode:           AppriseModeHTTP,
@@ -592,6 +597,11 @@ func TestSendTestNotificationAppriseHTTP(t *testing.T) {
 	}))
 	defer server.Close()
 
+	// Allow localhost for test server (SSRF protection normally blocks this)
+	if err := nm.UpdateAllowedPrivateCIDRs("127.0.0.1"); err != nil {
+		t.Fatalf("failed to configure allowlist: %v", err)
+	}
+
 	nm.SetAppriseConfig(AppriseConfig{
 		Enabled:        true,
 		Mode:           AppriseModeHTTP,