- Fix do-0x20-encode: clearing pending when toggling back to original (Disabled/Default)
- Do0x20EncodeDisplay: uncheck uses pending.OldValue when present
- EffectiveConfigFieldDisplay: use pending.OldValue as _valueAtActivation when re-entering with pending
- Effective config: validation errors/warnings in toolbar and save modal, revert from modal
- Custom displays: Do0x20EncodeDisplay (tri-state), KeyOnlyOrValueDisplay
- ExplicitToggleState, config/apply support for do-0x20-encode, option help and tests
- Move Client/Http, Services, Parsers under Infrastructure/ (Client, Services, Parsers)
- Move config helpers (DnsmasqConfKeys, DnsmasqOptionTooltips, DnsmasqFileEncoding, EffectiveConfigFieldBuilder) to Infrastructure/Helpers/Config; ApiJsonOptions to Helpers/Http
- Move Configuration types (ApplicationOptions, DnsmasqOptions, DnsmasqOptionsValidator) to Models/Config
- Merge Models/Status and Models/EffectiveConfig into Models/Dnsmasq and Models/Dnsmasq/EffectiveConfig
- Move Client/Models and Client/Services to Models/Client and Infrastructure/Services
- Move ConfigSetSnapshot, HostsSnapshot, ProcessRunResult, ManagedConfigContent from Infrastructure/Services/Abstractions to Models/Contracts
- Update all namespaces and usings; tests pass