Feat: Add XML guide to prompt, update model and deps

- Integrate `xml_guide.md` into the system prompt to improve diagram generation by providing detailed XML formatting rules.
- Change the default AI model for chat completions to `openai("gpt-4.1")`.
- Update AI SDK packages (`@ai-sdk/amazon-bedrock`, `@ai-sdk/google`, `ai`) and other dependencies.
- Add `bun.lock` to the repository.

package.json

@@ -9,17 +9,17 @@
     "lint": "next lint"
   },
   "dependencies": {
-    "@ai-sdk/amazon-bedrock": "^2.2.4",
-    "@ai-sdk/google": "^1.2.5",
-    "@ai-sdk/openai": "^1.2.5",
-    "@openrouter/ai-sdk-provider": "^0.4.5",
+    "@ai-sdk/amazon-bedrock": "^2.2.9",
+    "@ai-sdk/google": "^1.2.18",
+    "@ai-sdk/openai": "^1.3.22",
+    "@openrouter/ai-sdk-provider": "^0.4.6",
     "@radix-ui/react-dialog": "^1.1.6",
     "@radix-ui/react-scroll-area": "^1.2.3",
     "@radix-ui/react-slot": "^1.1.2",
     "@radix-ui/react-tooltip": "^1.1.8",
     "@vercel/analytics": "^1.5.0",
     "@xmldom/xmldom": "^0.9.8",
-    "ai": "^4.2.11",
+    "ai": "^4.3.16",
     "base-64": "^1.0.0",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",