MySQL editable grid and DDL parity

[openai0229]

Baseline

Match the original Chat2DB Community frontend and MySQL behavior at the pinned third-party commit. This is the next bounded slice after #4.

Scope

• Editable result-grid SQL generation for INSERT, UPDATE, and DELETE
• Editable result-grid execution through native mysql_async
• Table metadata needed by the original table editor
• Create and alter table SQL generation
• Drop, truncate, and copy table operations
• Create database/schema SQL and two-phase database/schema deletion
• View detail, create/alter SQL, and drop operations
• Historical Web and Tauri route parity for the original Community frontend
• Real Docker MySQL 8.4 product tests with Java remaining dormant
• Complete repository verification and normal CI

Constraints

• Preserve the original Community frontend and styles without modification.
• Use mysql_async for all MySQL data-plane execution.
• Validate identifiers and generate MySQL SQL from structured requests; do not trust client-composed object names.
• Enforce datasource read-only mode for every mutating operation.
• Do not trigger the macOS Package workflow.