feat(commands): QueryaCommandRegistry (CP-01) #743

Parent

#742
Template: docs/ui-parity-and-command-palette-issues.md CP-01

Goal

Central QueryaCommandRegistry for title, category, icon, shortcut label, isEnabled, and execute. Actions today are scattered across main_screen.dart shortcuts, the menubar, and SqlEditorCommandBridge.

Implementation

1. lib/core/actions/querya_command.dart — command model
2. lib/core/actions/querya_command_registry.dart — register + getAvailableCommands(context) + keyword/alias search
3. Seed a small core set (new connection, execute query, toggle sidebar, preferences, theme) so CP-02 has something to list
4. Tests: test/core/actions/querya_command_registry_test.dart

Acceptance

• Registry lists system + contextual commands
• isEnabled hides/disables (e.g. Execute Query only with an active editor)
• Search aliases (dark → toggle theme)