File history timeline (filelog) with diff-to-previous

- File history button in the preview header opens a per-file revision timeline
  (rev, changelist, action, user, date, description) with Diff to previous
- Backend p4 filelog -l; filelogRevs parser

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

src/i18n.ts

@@ -466,6 +466,9 @@ const D: Record<string, Tr> = {
   "Attach job to #{n}": { ru: "Привязать задачу к #{n}", de: "Job an #{n} anhängen", fr: "Associer un job à #{n}", es: "Adjuntar job a #{n}" },
   "Job ID": { ru: "ID задачи", de: "Job-ID", fr: "ID du job", es: "ID del job" },
   "Job {j} linked to #{n}.": { ru: "Задача {j} привязана к #{n}.", de: "Job {j} mit #{n} verknüpft.", fr: "Job {j} associé à #{n}.", es: "Job {j} vinculado a #{n}." },
+  "File history": { ru: "История файла", de: "Dateiverlauf", fr: "Historique du fichier", es: "Historial del archivo" },
+  "No history.": { ru: "Истории нет.", de: "Kein Verlauf.", fr: "Aucun historique.", es: "Sin historial." },
+  "Diff ↔ prev": { ru: "Diff ↔ пред.", de: "Diff ↔ vorher", fr: "Diff ↔ préc.", es: "Diff ↔ ant." },
   "Pick the Unreal project working folder first.": { ru: "Сначала выбери рабочую папку Unreal-проекта.", de: "Wähle zuerst den Arbeitsordner des Unreal-Projekts.", fr: "Choisis d'abord le dossier de travail du projet Unreal.", es: "Primero elige la carpeta de trabajo del proyecto Unreal." },
   "Disconnected from the server — retrying…": { ru: "Соединение с сервером потеряно — переподключаюсь…", de: "Verbindung zum Server verloren — erneuter Versuch…", fr: "Déconnecté du serveur — nouvelle tentative…", es: "Desconectado del servidor — reintentando…" },
 };