Guard viper with an RWMutex, make the singleton race-free and stop
NewManager replacing the global (add SetConfigManager), write saved
configs 0600, search CWD last, add ConfigFileUsed and Config.Validate,
nil-safe PathsConfig.Set, confine PathsConfig.Join, bound GetIPs DNS
lookup, and drop dead Unmarshal in SetConfig. Mark audit status.
- Add ServersConfig and ServerInstanceConfig structs
- Support configuring multiple named server instances
- Add global timeout defaults with per-instance overrides
- Add TLS configuration options (SSL cert/key, self-signed, AutoTLS)
- Add validation for server configurations
- Add helper methods for applying defaults and getting default server
- Add conversion helper to avoid import cycles