Add maintenance tools (VACUUM, ANALYZE, OPTIMIZE, REINDEX)

[datlechin]

Summary

Adds database maintenance operations accessible from the sidebar table context menu. Right-click a table > Maintenance submenu shows database-specific operations.

Database	Operations
PostgreSQL	VACUUM, ANALYZE, REINDEX, CLUSTER
MySQL/MariaDB	OPTIMIZE TABLE, ANALYZE TABLE, CHECK TABLE, REPAIR TABLE
SQLite	VACUUM, ANALYZE, REINDEX, Integrity Check

Each operation shows a confirmation sheet with:

• Operation name and target table
• Database-specific options (e.g. FULL, ANALYZE, VERBOSE for PostgreSQL VACUUM; check mode for MySQL CHECK TABLE)
• Live SQL preview
• Cancel / Execute buttons

Results shown via success/error alert after execution.

Architecture

Follows the existing truncate/drop pattern:

1. Plugin protocol: supportedMaintenanceOperations() + maintenanceStatements() with default nil implementations
2. Built-in plugin implementations for PostgreSQL, MySQL, SQLite
3. Context menu submenu (only shown when driver supports maintenance)
4. MaintenanceSheet confirmation dialog
5. Coordinator executes SQL directly via driver.execute(query:) (no query tab needed)

Databases without maintenance support (Redis, MongoDB, etc.) show no submenu.

Files

• New: TablePro/Views/Sidebar/MaintenanceSheet.swift
• Protocol: PluginDatabaseDriver.swift, DatabaseDriver.swift, PluginDriverAdapter.swift
• Plugins: PostgreSQLPluginDriver.swift, MySQLPluginDriver.swift, SQLitePlugin.swift
• UI: SidebarContextMenu.swift, MainContentView.swift, MainContentCoordinator.swift, MainContentCoordinator+SidebarActions.swift

Test plan

• PostgreSQL: right-click table > Maintenance > VACUUM > toggle FULL/ANALYZE/VERBOSE > verify SQL preview > Execute
• PostgreSQL: ANALYZE, REINDEX, CLUSTER on a table
• MySQL: OPTIMIZE TABLE, ANALYZE TABLE, CHECK TABLE (with mode picker), REPAIR TABLE
• SQLite: VACUUM, ANALYZE, REINDEX, Integrity Check
• Redis/MongoDB: verify no Maintenance submenu appears
• Read-only safe mode: verify maintenance operations are blocked
• Error handling: verify error alert on failure (e.g., CLUSTER without index)