MySQL Community editor payload and metadata fidelity

[openai0229]

Baseline

Close the remaining compatibility gaps found after #5 and #7 by matching the retained Chat2DB Community frontend payloads and MySQL 8.4 metadata behavior.

Scope

• Accept explicit null fields emitted by new Community table-editor columns and indexes
• Accept the frontend IN_VALUES result-grid operation
• Infer FIRST/AFTER column changes from drag-only array reordering
• Preserve UNSIGNED, ENUM/SET values, and composite primary-key order through native metadata
• Return the six Community MySQL view editor configurations and creation template
• Cover the exact frontend payloads through real Docker MySQL 8.4 tests

Constraints

• Preserve the original Community frontend and styles without modification.
• Keep every MySQL data-plane operation on mysql_async with Java dormant.
• Build executable DDL from structured and validated fields.
• Do not trigger the macOS Package workflow.