implement ucd-store-v2 with clean architecture #335
Description
This is a tracking issue for the implementation of @ucdjs/ucd-store-v2, a clean rewrite of the store package that addresses the inconsistencies and complexity issues in the current implementation.
The new package should be built from the ground up with consistent patterns, proper offline-first support, and a clear API design. This issue will track all the individual tasks needed to get the v2 package to feature parity and beyond.
Once all sub-tasks are complete and the package is stable, we can migrate consumers from the old package and eventually replace it entirely.