Entity imports now work across SQLite and Postgres

Entity imports between SQLite and Postgres were failing because the two databases store JSON differently. SQLite stores JSON columns as plain text, while Postgres stores them as native JSON objects. When exporting from SQLite, JSON fields came out as strings. When exporting from Postgres, they came out as parsed objects. The raw SQL import would then receive data in the wrong format for the target database.

A new normalization step now inspects each JSON column before insertion. String values (from SQLite exports) are parsed and re-serialized to canonical JSON. Object values (from Postgres exports) are serialized to strings. Both formats are then valid for any database driver handling json or simple-json columns.

This fix resolves silent data corruption that would otherwise produce malformed JSON stored in workflows, credentials, and other entities. The import pipeline in the CLI package now reliably transfers data between different database backends.