feat(entity): support json clob blob content type

[yuliuyi717-ux]

Summary

This PR adds explicit generator support for JSON-oriented CLOB fields by introducing a new blob content type: json.

What is included

• Added json as a valid fieldTypeBlobContent value.
• Added a CLI prompt option: A CLOB (JSON field) when selecting blob content for byte[] fields.
• Mapped fieldTypeBlobContent=json to TextBlob while preserving the json marker for template logic.
• Treated json as text-like (same as CLOB text) for:
  • faker/sample data generation,
  • content-type companion column generation,
  • liquibase column/load type generation,
  • DTO java type selection,
  • client-side content-type field generation.
• Added targeted tests for conversion and field preparation behavior.

Why

TextBlob can store JSON payloads, but generation logic currently only distinguishes text / binary-oriented blob content.
This change makes JSON-CLOB usage explicit and consistent across generation paths while keeping existing TextBlob storage behavior.

Refs #14526

Validation

npx -y node@22 ./node_modules/.bin/tsc -p tsconfig.spec.json --noEmit
npx -y node@22 ./node_modules/.bin/esmocha generators/base-application/support/prepare-field.spec.ts generators/entity/single-entity.spec.ts generators/liquibase/generator.spec.ts --no-insight --forbid-only