Integrate chat panel into OperatorCommandCenter

## Task Integrate the `SessionChatPanel` component into the operator's `OperatorCommandCenter` interface. ## Layout Changes Modify the operator UI to include a collapsible chat panel: ``` ┌─────────────────────────────────────────┬──────────────┐ │ │ │ │ Guest Video │ Chat │ │ │ Panel │ │ │ (collapse) │ │ [Self PiP] │ │ ├─────────────────────────────────────────┴──────────────┤ │ [Mic] [Cam] | [Mute Guest] [Screen] [Lang] [Rec] [End]│ └────────────────────────────────────────────────────────┘ ``` ## Integration Points 1. Add chat toggle button to control bar 2. Pass session props to `SessionChatPanel` 3. Fetch initial messages on mount 4. Use NATS for real-time subscription (operator has device context) 5. Handle session ended state (show history, disable input) ## Props to Pass ```jsx <SessionChatPanel sessionId={sessionId} participantType="operator" participantName={currentUser.username} initialMessages={messages} isCollapsed={chatCollapsed} onToggle={() => setChatCollapsed(!chatCollapsed)} disabled={sessionEnded} /> ``` ## Files to Modify - `app/javascript/components/remote_support/OperatorCommandCenter.jsx` - `app/components/remote_support/session_detail_component.html.haml` (pass initial messages) - `app/components/remote_support/session_detail_component.rb` (fetch messages)