Add Terminal Connection Status Indicator

Part of requirement FR7 ↗

User Story: As a user, I want the system to notify me whether the terminal is currently connected or disconnected, so that I am aware of the device's connection status.

Acceptance Criteria:

• A connection confirmation message appears on the terminal when an app is successfully connected.
• A connection confirmation message appears on the app when a terminal is successfully connected.
• An icon resembling a connection is displayed in the app while a connection is active.
• An icon resembling a connection is displayed in the terminal while a connection is active.