Add message timestamps

[dchaudhari7177]

Closes #16.

The issue is a one-liner, so here is the reading I worked to: chat messages show who and what but never when, which matters in a room that stays open for hours and whose history you can scroll back through.

The data already existed

No backend change was needed. Message.model.ts is declared with { timestamps: true }, so every message document already carries createdAt, and both paths that reach the client already send it:

• loadMessage.controller.ts returns the documents from Message.find(...)
• sendMessage.controller.ts emits the created document over new-message

The only thing missing was that the frontend never declared or displayed the field. So this is a two-file frontend change.

What changed

room.store.ts — MessageType gains createdAt: string, with a comment noting where it comes from so it does not look like a field someone must now populate by hand.

ChatPanel.tsx — the username line becomes a flex row holding the name and a timestamp:

<time dateTime={message.createdAt} title={formatMessageTimestamp(message.createdAt)}>
  {formatMessageTime(message.createdAt)}
</time>

Choices worth stating:

• Hours and minutes only in the visible label. It sits inline beside the username in a narrow side panel, so a full date would crowd the name off the line.
• Full local date and time on hover (title), because a room can outlive a day and 09:14 alone does not say which one.
• A real <time dateTime> element, so the machine-readable ISO value stays available to assistive technology and is not reduced to decorative text.
• toLocaleTimeString / toLocaleString with no fixed locale, so the format follows the viewer's own settings rather than hard-coding a 12- or 24-hour convention.
• Bad input renders nothing. parseMessageDate returns null for a missing or unparseable value and the <time> element is skipped, so an unexpected payload shows no timestamp rather than the string Invalid Date.

No change to the store's send path, the socket wiring, the backend, or the existing auto-scroll behaviour.

Verification

Windows 11, Node v24.17.0, TypeScript 6.0.3.

npm run build reports 4 errors before my change and the same 4 after — all TS7016: Could not find a declaration file for module 'react-icons/...', in Hero.tsx, RoomPage.tsx (×2) and the pre-existing FaCrown import at ChatPanel.tsx:4. They are pre-existing on main and unrelated; my change introduces none, and nothing in the new code is flagged.

You may want @types/react-icons (or a declare module shim) as a separate fix — happy to open that as its own issue if it is not already known.

I was not able to run the app end to end against MongoDB to screenshot the result, so the rendering is verified by types and by reading the payload shape rather than visually. Say the word if you would like the timestamp styled differently.