Add Events on Root Element and customisations

### 🛠️ Feature Request: Enhance Event Hooks, Form Controls, and Dialog Customization

#### 1. Add Root-Level Events (`onload`, `onrefresh`)
Adding lifecycle events like `onload` and `onrefresh` at the root level would help run checks (e.g., checking if a POS session is open) before loading the page. This improves flexibility and backend interaction.

#### 2. Improve Form Control Options
It would be great to support dynamic and conditional options in form inputs like `Select`. This would allow developers to adjust form inputs based on roles, backend data, or other logic.

#### 3. Make Dialog Components Customizable
Currently, dialog components are hard to customize. If we could insert or modify components inside them, it would help in creating custom modals, forms, or interactive workflows.