Large host files mounted via Docker volumes caused the storages page to
become unusable — full file content was stored in the encrypted mediumText
column and serialised into the Livewire payload, crashing the browser.
- Add MAX_CONTENT_SIZE (5 MiB), BINARY_PLACEHOLDER, and TOO_LARGE_PLACEHOLDER
constants to LocalFileVolume
- Check remote file size via stat/wc before cat in loadStorageOnServer and
saveStorageOnServer; store placeholder instead of content when limit exceeded
- Expose is_too_large computed attribute (appended for Livewire serialisation)
- Guard submit, instantSave, and syncData in FileStorage Livewire component
- Truncate oversized content in Storage::refreshStorages to prevent payload bloat
- Show distinct warning banner in file-storage blade; mark textarea readonly and
hide Save/Convert buttons for too-large files
- Add unit tests covering constants, computed flags, and toArray serialisation
Fixes#4701
