fix(knowledge-service): resolve semantic cache collision by partitioning content hash by traceType and PromptVersion

src/NexusReader.Infrastructure/Services/KnowledgeService.cs

@@ -85,7 +85,8 @@ public class KnowledgeService : IKnowledgeService
 
         using var dbContext = await _dbContextFactory.CreateDbContextAsync(cancellationToken);
         var normalizedText = text.Trim();
-        var hash = ContentHasher.ComputeHash(normalizedText);
+        var hashInput = $"{normalizedText}:{traceType}:{PromptVersion}";
+        var hash = ContentHasher.ComputeHash(hashInput);
 
         // 1. Check Cache
         var cached = await dbContext.SemanticKnowledgeCache