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_load_test.wren

@@ -0,0 +1,91 @@
+// retoor <retoor@molodetz.nl>
+
+import "websocket" for WebSocket
+import "io" for Stdout
+
+var host = "ws://127.0.0.1:8080"
+var totalMessages = 50000
+var warmupMessages = 100
+
+System.print("=== WebSocket Extreme Load Test ===")
+System.print("Target: %(host)")
+System.print("Messages: %(totalMessages) (warmup: %(warmupMessages))")
+System.print("")
+Stdout.flush()
+
+var ws = WebSocket.connect(host)
+System.print("Connected")
+Stdout.flush()
+
+var i = 0
+while (i < warmupMessages) {
+  ws.send("warmup%(i)")
+  ws.receive()
+  i = i + 1
+}
+System.print("Warmup complete")
+Stdout.flush()
+
+var errors = 0
+var minTime = 999999
+var maxTime = 0
+var totalTime = 0
+var times = []
+
+var startTime = System.clock
+
+i = 0
+while (i < totalMessages) {
+  var msgStart = System.clock
+  ws.send("msg%(i)")
+  var response = ws.receive()
+  var msgEnd = System.clock
+  var elapsed = msgEnd - msgStart
+
+  if (response == null || !response.isText) {
+    errors = errors + 1
+  } else {
+    times.add(elapsed)
+    totalTime = totalTime + elapsed
+    if (elapsed < minTime) minTime = elapsed
+    if (elapsed > maxTime) maxTime = elapsed
+  }
+
+  if (i > 0 && i % 2000 == 0) {
+    var progress = (i * 100 / totalMessages).floor
+    var currentRate = i / (System.clock - startTime)
+    System.print("  Progress: %(progress) percent (%(currentRate.floor) msg/sec)")
+    Stdout.flush()
+  }
+
+  i = i + 1
+}
+
+var endTime = System.clock
+var totalElapsed = endTime - startTime
+
+ws.close()
+
+times.sort()
+var p50 = times[(times.count * 0.5).floor]
+var p90 = times[(times.count * 0.9).floor]
+var p95 = times[(times.count * 0.95).floor]
+var p99 = times[(times.count * 0.99).floor]
+var avgTime = totalTime / times.count
+
+System.print("")
+System.print("=== Results ===")
+System.print("Total messages:    %(totalMessages)")
+System.print("Errors:            %(errors)")
+System.print("Total time:        %(totalElapsed)s")
+System.print("Throughput:        %((totalMessages / totalElapsed).floor) msg/sec")
+System.print("")
+System.print("=== Latency (per message round-trip) ===")
+System.print("Min:               %((minTime * 1000000).floor) us")
+System.print("Max:               %((maxTime * 1000000).floor) us")
+System.print("Avg:               %((avgTime * 1000000).floor) us")
+System.print("P50:               %((p50 * 1000000).floor) us")
+System.print("P90:               %((p90 * 1000000).floor) us")
+System.print("P95:               %((p95 * 1000000).floor) us")
+System.print("P99:               %((p99 * 1000000).floor) us")
+Stdout.flush()