feat: implement lazy virtual drive metadata synchronization

[egalvis27]

What is Changed / Added

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Lazy directory hydration

• Added LazyVirtualDriveHydrator to resolve virtual-drive paths and hydrate directory children on demand.
• readDirectory resolves a directory, refreshes its children when the cached state is stale, and returns local folder/file entries.
• ensurePathLoaded hydrates a path's parent directory before retrying file lookups.
• Added per-directory in-flight request deduplication, keyed by folderId:statusScope, so concurrent FUSE operations share the same remote hydration request.

Remote directory persistence

• Added hydrateDirectoryChildren, which:

  • Fetches folder content from the Drive API.
  • Filters non-existing or removed folders/files.
  • Maps API DTOs into remote sync entities.
  • Persists folders and files sequentially through SQLite batch operations.
  • Removes stale local descendants before storing the refreshed children.
  • Invalidates cached directory state for deleted descendant folders.
  • Recreates local Folder and File entities and updates the corresponding repositories.
  • Marks directory state as loaded on success or errored on failure.

• Added dedicated remote file/folder mappers with direct tests for:

  • Existing status assignment.
  • Nullable fileId normalization.
  • File-size conversion from API string values.

FUSE operation integration

• Updated opendir to use lazy hydration before listing local directory entries.
• Updated getAttributes to hydrate the parent directory and retry local file/folder lookup when an entry is not initially present.
• Updated open to hydrate and retry file lookup before returning ENOENT.
• Preserved FUSE-specific errors from the hydration layer instead of converting them into generic I/O errors.

Why

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The Virtual Drive must remain usable while the remote account contains a very large number of files and folders.

Previously, FUSE operations depended on the local catalog being fully synchronized before users could browse directories or access files. This change allows the application to fetch and persist only the directory children required by the current filesystem operation.

The directory-state cache avoids repeatedly fetching recently loaded folders, while the in-flight request registry prevents duplicate API calls when multiple FUSE requests target the same stale directory concurrently. Stale-child cleanup and directory-state invalidation keep the local cache coherent after remote changes.

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[sonarqubecloud]

Quality Gate failed

Failed conditions
66.1% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud