Add bulk video indexing

[haroon10725]

VidXP currently starts indexing one video at a time. Add bulk indexing for selected videos or all eligible videos in a repository.

Expected behavior:

• Skip videos already indexed with the current configuration unless reindexing is requested.
• Show overall progress while retaining per-video status.
• Preserve successful results if another video fails.
• Allow failed videos to be retried independently.
• Avoid duplicating existing indexing behavior.

The initial interface may be CLI or browser UI, provided the underlying behavior remains reusable by other VidXP interfaces.