feat(config): internal/config (load/save atomik + validasi) — wiring bahasa/suara/animasi + doctor baca config

internal/i18n/locales/en.yaml

@@ -61,6 +61,7 @@ toast:
   demoTitle: "✔ [ SUCCESS ] Conversion Saved"
   demoBody: "Stack 'web-app' saved to ~/.tia/stacks/web-app/"
   dockerError: "✖ [ FAILED ] Docker"
+  configError: "⚠ [ WARNING ] Config problem — using defaults"
 
 activity:
   coming: "Docker events listener coming (Phase 2)."
@@ -84,6 +85,7 @@ doctor:
   dockerDaemonUnreachable: "daemon not responding: %v"
   dockerOk: "engine %s (API %s) · %d/%d containers running · %d images"
   stacksMissing: "%s (missing — created during onboarding)"
+  configMissing: "%s (missing — using defaults)"
 
 cli:
   unknownCommand: "unknown command: %q"