feat: Add presence heartbeat for Matrix online status

- matrix-gateway: POST /internal/matrix/presence/online endpoint
- usePresenceHeartbeat hook with activity tracking
- Auto away after 5 min inactivity
- Offline on page close/visibility change
- Integrated in MatrixChatRoom component

node_modules/yocto-queue/index.js

@@ -0,0 +1,68 @@
+class Node {
+	/// value;
+	/// next;
+
+	constructor(value) {
+		this.value = value;
+
+		// TODO: Remove this when targeting Node.js 12.
+		this.next = undefined;
+	}
+}
+
+class Queue {
+	// TODO: Use private class fields when targeting Node.js 12.
+	// #_head;
+	// #_tail;
+	// #_size;
+
+	constructor() {
+		this.clear();
+	}
+
+	enqueue(value) {
+		const node = new Node(value);
+
+		if (this._head) {
+			this._tail.next = node;
+			this._tail = node;
+		} else {
+			this._head = node;
+			this._tail = node;
+		}
+
+		this._size++;
+	}
+
+	dequeue() {
+		const current = this._head;
+		if (!current) {
+			return;
+		}
+
+		this._head = this._head.next;
+		this._size--;
+		return current.value;
+	}
+
+	clear() {
+		this._head = undefined;
+		this._tail = undefined;
+		this._size = 0;
+	}
+
+	get size() {
+		return this._size;
+	}
+
+	* [Symbol.iterator]() {
+		let current = this._head;
+
+		while (current) {
+			yield current.value;
+			current = current.next;
+		}
+	}
+}
+
+module.exports = Queue;