[Feature] Let `immich upload` check what's already on the server without uploading (e.g. `--no-upload`)

I have searched the existing feature requests, both open and closed, to make sure this is not a duplicate request. • Yes The feature immich upload --delete and --delete-duplicates only ever run as a side effect of an upload, so checking a directory against the server and acting on what's already there means uploading every new file in it first. There's no way to ask "which of these do I already have?" and act on the answer without that. uploadBatch already computes exactly the split this would need (packages/cli/src/commands/asset.ts:69–78): checkForDuplicates already produces the newFiles / duplicates split; deleteFiles already knows how to delete duplicates when --delete-duplicates is set. The only thing standing between "check" and "act on what the server already has" is the uploadFiles(newFiles, options) call on line 71. This is proposed as a small flag, not a new subsystem: skip that one call, leave newFiles on disk and reported…