chore(common): add system prompt

Author: ntacheva

common/microsoft-extensions-ai-integration/AIPromptIntegration/AIPromptIntegration/Components/Pages/Home.razor

@@ -1,6 +1,7 @@
 @page "/"
 
-<TelerikAIPrompt PromptSuggestions="@Suggestions">
+<TelerikAIPrompt PromptSuggestions="@Suggestions"
+                 SystemPrompt="@SystemPrompt">
 </TelerikAIPrompt>
 
 @code {
@@ -12,4 +13,6 @@
         "Suggest improvements for a team productivity strategy.",
         "Draft an email to request feedback on a project."
     };
+
+    private string SystemPrompt { get; set; } = "You are an AI assistant embedded in a Blazor application using Microsoft.Extensions.AI. Your purpose is to provide clear, concise, and helpful responses to user queries. Always maintain a professional yet friendly tone. If a user asks for coding help, provide well-structured examples in C# when relevant. If a question is unclear, politely ask for clarification. Do not provide opinions, and always prioritize accuracy and reliability in your responses.";
 }