feat: add cJSON and SQLite amalgamation source files under deps/

Add the cJSON library (cJSON.c, cJSON.h) and SQLite amalgamation
(sqlite3.c, sqlite3.h, sqlite3ext.h, shell.c) as vendored dependencies
in the deps/ directory for use by the project build system.

example/websocket_chat_server.wren

@@ -0,0 +1,95 @@
+// retoor <retoor@molodetz.nl>
+
+import "websocket" for WebSocket, WebSocketServer
+import "scheduler" for Scheduler
+import "timer" for Timer
+
+var port = 8080
+var clients = []
+var clientId = 0
+
+System.print("=== WebSocket Chat Server ===")
+System.print("Listening on ws://0.0.0.0:%(port)")
+System.print("Clients can send messages that get broadcast to all others.\n")
+
+var broadcast = Fn.new { |sender, message|
+  var i = 0
+  while (i < clients.count) {
+    var client = clients[i]
+    if (client["ws"].isOpen && client["id"] != sender) {
+      client["ws"].send(message)
+    }
+    i = i + 1
+  }
+}
+
+var removeClient = Fn.new { |id|
+  var i = 0
+  while (i < clients.count) {
+    if (clients[i]["id"] == id) {
+      clients.removeAt(i)
+      break
+    }
+    i = i + 1
+  }
+}
+
+var handleClient = Fn.new { |ws, id|
+  var client = {"ws": ws, "id": id, "name": "User%(id)"}
+  clients.add(client)
+
+  System.print("[%(client["name"])] Connected (%(clients.count) clients online)")
+  broadcast.call(id, "*** %(client["name"]) joined the chat ***")
+
+  while (ws.isOpen) {
+    var msg = ws.receive()
+
+    if (msg == null || msg.isClose) {
+      break
+    }
+
+    if (msg.isText) {
+      var text = msg.text
+
+      if (text.startsWith("/name ")) {
+        var oldName = client["name"]
+        client["name"] = text[6..-1]
+        broadcast.call(-1, "*** %(oldName) is now known as %(client["name"]) ***")
+        ws.send("Name changed to %(client["name"])")
+      } else if (text == "/who") {
+        var names = []
+        for (c in clients) {
+          names.add(c["name"])
+        }
+        ws.send("Online: " + names.join(", "))
+      } else if (text == "/quit") {
+        ws.send("Goodbye!")
+        break
+      } else {
+        var chatMsg = "[%(client["name"])]: %(text)"
+        System.print(chatMsg)
+        broadcast.call(id, chatMsg)
+        ws.send(chatMsg)
+      }
+    }
+  }
+
+  removeClient.call(id)
+  System.print("[%(client["name"])] Disconnected (%(clients.count) clients online)")
+  broadcast.call(id, "*** %(client["name"]) left the chat ***")
+}
+
+var server = WebSocketServer.bind("0.0.0.0", port)
+
+while (true) {
+  var ws = server.accept()
+
+  if (ws != null) {
+    clientId = clientId + 1
+    var id = clientId
+
+    Scheduler.add {
+      handleClient.call(ws, id)
+    }
+  }
+}