feat: Implement a modular skill system with hotword detection, streaming text output, and enhanced logging.

Core/Skills/ISkill.cs

@@ -0,0 +1,13 @@
+namespace Toak.Core.Skills;
+
+public interface ISkill
+{
+    string Name { get; }
+    string Description { get; }
+    string[] Hotwords { get; }
+    
+    bool HandlesExecution { get; }
+    
+    string GetSystemPrompt(string rawTranscript);
+    void Execute(string llmResult);
+}