Add VRC OSC tooling

VRWT_Tool/VRC_OSC/src/common/runtime_log.py

@@ -0,0 +1,19 @@
+from datetime import datetime
+
+from common.project_paths import RUNTIME_LOG_FILE
+
+
+def appendRuntimeLog(title, text):
+    RUNTIME_LOG_FILE.parent.mkdir(parents=True, exist_ok=True)
+
+    now = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+    body = str(text).strip()
+    if not body:
+        body = "(empty)"
+
+    with RUNTIME_LOG_FILE.open("a", encoding="utf-8") as file:
+        file.write(f"\n[{now}] {title}\n")
+        file.write(body)
+        file.write("\n")
+
+    return RUNTIME_LOG_FILE