Make photo upload limit configurable via admin settings (#40)

frontend/src/i18n/locales/en.json

@@ -48,7 +48,7 @@
     "noCategory": "No category",
     "eventSpecific": "(Event specific)",
     "clickToUpload": "Click to upload or drag and drop",
-    "fileRequirements": "JPEG, PNG or WebP (max 50MB per file)",
+    "fileRequirements": "JPEG, PNG or WebP (max 50MB per file, {{limit}} files per upload)",
     "selectedFiles": "Selected files",
     "uploading": "Uploading...",
     "uploadComplete": "Upload complete!",
@@ -59,9 +59,11 @@
     "externalImportInfo": "All pictures from the selected folder will be imported.",
     "selectExternalFolder": "Select external folder under /external-media",
     "importFromSelectedFolder": "Import from selected folder",
-    "maxFilesReached": "Maximum 500 files allowed",
-    "someFilesSkipped": "Some files were skipped (500 file limit)",
-    "tooManyFiles": "Maximum 500 files can be uploaded at once",
+    "maxFilesReached": "Maximum {{limit}} files allowed",
+    "someFilesSkipped": "Only {{allowed}} more files can be added (limit {{limit}})",
+    "tooManyFiles": "Maximum {{limit}} files can be uploaded at once",
+    "limitInfo": "{{selected}} of {{limit}} files selected ({{remaining}} remaining)",
+    "limitReached": "Upload limit reached ({{limit}} files per batch)",
     "uploadingChunks": "Uploading {{count}} files in {{total}} batches..."
   },
   "navigation": {
@@ -453,6 +455,8 @@
       "defaultExpirationHelp": "How long galleries remain active by default",
       "maxFileSize": "Max File Size (MB)",
       "maxFileSizeHelp": "Maximum size per uploaded photo",
+      "maxFilesPerUpload": "Max Files per Upload",
+      "maxFilesPerUploadHelp": "Maximum number of photos allowed in a single upload batch (1-{{max}}).",
       "allowedFileTypes": "Allowed File Types",
       "allowedFileTypesHelp": "Comma-separated list of file extensions",
       "featureToggles": "Feature Toggles",