fix: handle foreign key violations as 400 Bad Request instead of 500

Foreign key constraint violations (PostgreSQL error 23503) from user input
(e.g., POST /rest/people with a non-existent companyId) were falling through
to the generic PostgresException catch-all, which returned a 500 Internal
Server Error with an unhelpful "Data validation error." message.

Add a specific handler for FOREIGN_KEY_VIOLATION that returns a TwentyORMException
with INVALID_INPUT code, resulting in a 400 Bad Request with a descriptive message.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

packages/twenty-server/src/engine/twenty-orm/error-handling/compute-twenty-orm-exception.ts

@@ -58,6 +58,13 @@ export const computeTwentyORMException = async (
       );
     }
 
+    if (errorCode === POSTGRESQL_ERROR_CODES.FOREIGN_KEY_VIOLATION) {
+      return new TwentyORMException(
+        'Record violates a foreign key constraint. Please ensure related records exist.',
+        TwentyORMExceptionCode.INVALID_INPUT,
+      );
+    }
+
     if (
       isDefined(errorCode) &&
       Object.values(POSTGRESQL_ERROR_CODES).includes(errorCode)