feat: add file upload progress toast with per-file tracking (#93)

Replaced the hidden dropzone-only progress bar with a floating
upload toast that appears at the bottom-right corner whenever
files are being uploaded (button or drag-and-drop).

Features:
- Per-file progress bar with real byte-level tracking via XHR
- Spinning icon while uploading, green check on success, red on error
- Overall progress bar and file counter in the footer
- Auto-hides 4 seconds after all uploads complete
- Dismiss button to minimise the toast
- Works for both file and folder uploads
- i18n keys added to all 8 locale files
- Service worker cache bumped to v3

static/locales/de.json

@@ -16,6 +16,8 @@
     "upload": "Hochladen",
     "upload_files": "Dateien hochladen",
     "upload_folder": "Ordner hochladen",
+    "upload.uploading": "Wird hochgeladen...",
+    "upload.complete": "{count} / {total} hochgeladen",
     "rename": "Umbenennen",
     "move": "Verschieben nach...",
     "move_to": "Verschieben nach",

static/locales/en.json

@@ -16,6 +16,8 @@
     "upload": "Upload",
     "upload_files": "Upload files",
     "upload_folder": "Upload folder",
+    "upload.uploading": "Uploading...",
+    "upload.complete": "{count} / {total} uploaded",
     "rename": "Rename",
     "move": "Move to...",
     "move_to": "Move to",

static/locales/es.json

@@ -135,6 +135,8 @@
     "upload": "Subir",
     "upload_files": "Subir archivos",
     "upload_folder": "Subir carpeta",
+    "upload.uploading": "Subiendo...",
+    "upload.complete": "{count} / {total} subidos",
     "rename": "Renombrar",
     "move": "Mover a...",
     "move_to": "Mover a",

static/locales/fa.json

@@ -16,6 +16,8 @@
     "upload": "بارگذاری",
     "upload_files": "بارگذاری پرونده‌ها",
     "upload_folder": "بارگذاری پوشه",
+    "upload.uploading": "...در حال بارگذاری",
+    "upload.complete": "{count} / {total} بارگذاری شد",
     "rename": "تغییر نام",
     "move": "انتقال به...",
     "move_to": "انتقال به",

static/locales/fr.json

@@ -16,6 +16,8 @@
     "upload": "Téléverser",
     "upload_files": "Téléverser des fichiers",
     "upload_folder": "Téléverser un dossier",
+    "upload.uploading": "Envoi en cours...",
+    "upload.complete": "{count} / {total} envoyés",
     "rename": "Renommer",
     "move": "Déplacer vers...",
     "move_to": "Déplacer vers",

static/locales/it.json

@@ -16,6 +16,8 @@
  "upload": "Carica",
  "upload_files": "Carica file",
  "upload_folder": "Carica cartella",
+ "upload.uploading": "Caricamento...",
+ "upload.complete": "{count} / {total} caricati",
  "rename": "Rinomina",
  "move": "Sposta in...",
  "move_to": "Sposta in",
@@ -311,7 +313,7 @@
  "fa": "Persiano",
  "fr": "Francese",
  "de": "Tedesco",
- "pt": "Portoghese",
+ "pt": "Portoghese"
  "it": "Italiano"
  }
  },

static/locales/pt.json

@@ -16,6 +16,8 @@
     "upload": "Enviar",
     "upload_files": "Enviar arquivos",
     "upload_folder": "Enviar pasta",
+    "upload.uploading": "Enviando...",
+    "upload.complete": "{count} / {total} enviados",
     "rename": "Renomear",
     "move": "Mover para...",
     "move_to": "Mover para",

static/locales/zh.json

@@ -16,6 +16,8 @@
     "upload": "上传",
     "upload_files": "上传文件",
     "upload_folder": "上传文件夹",
+    "upload.uploading": "上传中...",
+    "upload.complete": "{count} / {total} 已上传",
     "rename": "重命名",
     "move": "移动到...",
     "move_to": "移动到",