Tier 0 bug fixes, plugin de-duplication and splits, and sync test coverage

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- JSON file import works again. It failed to load in 0.48.0.
+- SQL export quotes empty or malformed values in numeric columns instead of writing them unquoted, which could produce invalid INSERT statements.
 ### Added
 
 - Each filter row has a checkbox to turn it on or off and an Apply button to filter by just that row. The main Apply runs every active filter, and disabled filters stay in the panel for later. (#1561)