Syncing artifacts can be time-consuming, and if collector executions overlap
for the same product, race conditions and resource spikes may occur. The goal
of this task is to ensure that /sync/images/<product_key> cannot run
concurrently.

The existing SBOM sync logic already implemented a lock, so this commit
refactors that mechanism into a reusable decorator and applies it to image
sync. This enables product-scoped locking and ensures safe, non-overlapping
collector execution without blocking other products running in parallel.