fix: Python 3.14 互換性問題への対応（バージョン制限と .python-version 追加）

Author: Antigravity Agent

.python-version

@@ -0,0 +1 @@
+3.12

pyproject.toml

@@ -4,7 +4,7 @@ version = "0.2.0"
 description = "Nexus Ark: AI Persona Interaction System"
 authors = [{ name = "Kenomendako", email = "kenomendako@example.com" }]
 readme = "README.md"
-requires-python = ">=3.11"
+requires-python = ">=3.11, <3.14"
 dependencies = [
     # --- Core Frameworks ---
     "gradio==5.47.0",