Fix build success detection + minimizable build window + de-dupe event logs

- build_sln now trusts UnrealBuildTool's "Result: Succeeded" (and absence of
  real compile errors) over MSBuild's exit code, which is non-zero for a side
  project even when the UE game module built fine.
- Fixed double event-listener registration (async unlisten under StrictMode)
  that duplicated every p4-log / p4-transfer / build-log line.
- Build overlay can be minimized to a small floating chip (spinner while
  building, ✓/✗ when done), click to expand, × to dismiss.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/i18n.ts

@@ -25,6 +25,7 @@ const D: Record<string, Tr> = {
   "Minimize": { ru: "Свернуть", de: "Minimieren", fr: "Réduire", es: "Minimizar" },
   "Maximize": { ru: "Развернуть", de: "Maximieren", fr: "Agrandir", es: "Maximizar" },
   "Close": { ru: "Закрыть", de: "Schließen", fr: "Fermer", es: "Cerrar" },
+  "Expand": { ru: "Развернуть", de: "Erweitern", fr: "Agrandir", es: "Expandir" },
   "Theme": { ru: "Тема", de: "Thema", fr: "Thème", es: "Tema" },
   "Restoring session…": { ru: "Восстановление сессии…", de: "Sitzung wird wiederhergestellt…", fr: "Restauration de la session…", es: "Restaurando sesión…" },
   // startup splash