chore: gofmt the tree, clear staticcheck, add a CI gofmt gate

Nine files had drifted from gofmt and nothing checked; nine staticcheck
findings were live (three dead symbols, capitalization, a redundant
Sprintf, two literal-to-conversion sites, a nil test context). Fix all
of them and make CI fail on unformatted Go so this cannot re-drift.

cmd/felis/backupnow.go

@@ -51,7 +51,7 @@ func resolveInternalAPI(ctx context.Context, cl client.Client, controlNamespace
 	}
 	token = string(sec.Data[naming.ServiceTokenSecretKey])
 	if token == "" {
-		return "", "", fmt.Errorf("Secret %s has no %s key", naming.ServiceTokenSecretName, naming.ServiceTokenSecretKey)
+		return "", "", fmt.Errorf("secret %s has no %s key", naming.ServiceTokenSecretName, naming.ServiceTokenSecretKey)
 	}
 
 	return fmt.Sprintf("http://%s:%d", ip, platform.APIInternalPort), token, nil

cmd/felis/breakglass.go

@@ -571,12 +571,10 @@ type breakGlassResult struct {
 	backupStatus string
 
 	// Cloudflare-specific edge detail (set only when connectMethod is Cloudflare)
-	edgeConfigured    bool
-	edgeAud           string
-	edgeRoutedHosts   []string
-	edgeConfigPath    string
-	edgePanelHostname string
-	edgeAdminHostname string
+	edgeConfigured  bool
+	edgeAud         string
+	edgeRoutedHosts []string
+	edgeConfigPath  string
 }
 
 type consoleMode string