feat: implement AI-driven knowledge extraction service with semantic caching and persistent storage

src/NexusReader.Application/Abstractions/Services/IKnowledgeService.cs

@@ -0,0 +1,9 @@
+using FluentResults;
+using NexusReader.Application.DTOs.AI;
+
+namespace NexusReader.Application.Abstractions.Services;
+
+public interface IKnowledgeService
+{
+    Task<Result<KnowledgePacket>> GetKnowledgeAsync(string text, CancellationToken cancellationToken = default);
+}