feat(logging): make error-logs-max-files configurable

- Add ErrorLogsMaxFiles config field with default value 10
- Support hot-reload via config file changes
- Add Management API: GET/PUT/PATCH /v0/management/error-logs-max-files
- Maintain SDK backward compatibility with NewFileRequestLogger (3 params)
- Add NewFileRequestLoggerWithOptions for custom error log retention

When request logging is disabled, forced error logs are retained up to
the configured limit. Set to 0 to disable cleanup.

internal/config/config.go

@@ -51,6 +51,10 @@ type Config struct {
 	// When exceeded, the oldest log files are deleted until within the limit. Set to 0 to disable.
 	LogsMaxTotalSizeMB int `yaml:"logs-max-total-size-mb" json:"logs-max-total-size-mb"`
 
+	// ErrorLogsMaxFiles limits the number of error log files retained when request logging is disabled.
+	// When exceeded, the oldest error log files are deleted. Default is 10. Set to 0 to disable cleanup.
+	ErrorLogsMaxFiles int `yaml:"error-logs-max-files" json:"error-logs-max-files"`
+
 	// UsageStatisticsEnabled toggles in-memory usage aggregation; when false, usage data is discarded.
 	UsageStatisticsEnabled bool `yaml:"usage-statistics-enabled" json:"usage-statistics-enabled"`
 
@@ -502,6 +506,7 @@ func LoadConfigOptional(configFile string, optional bool) (*Config, error) {
 	cfg.Host = "" // Default empty: binds to all interfaces (IPv4 + IPv6)
 	cfg.LoggingToFile = false
 	cfg.LogsMaxTotalSizeMB = 0
+	cfg.ErrorLogsMaxFiles = 10
 	cfg.UsageStatisticsEnabled = false
 	cfg.DisableCooling = false
 	cfg.AmpCode.RestrictManagementToLocalhost = false // Default to false: API key auth is sufficient
@@ -550,6 +555,10 @@ func LoadConfigOptional(configFile string, optional bool) (*Config, error) {
 		cfg.LogsMaxTotalSizeMB = 0
 	}
 
+	if cfg.ErrorLogsMaxFiles < 0 {
+		cfg.ErrorLogsMaxFiles = 10
+	}
+
 	// Sync request authentication providers with inline API keys for backwards compatibility.
 	syncInlineAccessProvider(&cfg)