Initial import of Shirobana bot backend

Include utility modules, shared channels, prompts, read-only skills, wardrobe memory and regression tests. Externalize legacy credentials and exclude private runtime state.

bot-utility/settings.example.json

@@ -0,0 +1,13 @@
+{
+  "tg_token": "",
+  "tg_proxy": "",
+  "admin": {
+    "tg": [],
+    "qq": []
+  },
+  "chat_mode": {
+    "default": "command",
+    "admin": "chat",
+    "group": "command"
+  }
+}