update model version from the app

[tiero]

Now the only way to download a new version of a model, is to delete the data directory (or specific model folder) manually.

We should allow to

a) check if a new update is available
b) allow users to remove old and download new ones

These should be Tauri commands, eventually wrapped into the UI

The update process can be built more efficiently if we have a checksum system in place
#423

[swarnimarun]

Notes:

• Currently it's possible to do the above, by deleting the service and redownloading it, but you never get notified if the local version maybe stale.
• We should make it possible to only update specific files such as just updating the binaries and keep the weights from being deleted and redownloaded.
• We can't use checksums for a while hence we can store local metadata about last used url to get around and get proper url-based versioning working.

Future Works may include:

• We should be able to get ota updates and patches for large weight files so that we don't have to ever redownload a binary locally.
• We should support checksum validated urls.
• We should provide ability to switch to specific binary or model versions to the user??