feat: implement semantic search, knowledge unit extraction, and visualization components

src/NexusReader.Domain/Entities/SemanticKnowledgeCache.cs

@@ -1,4 +1,5 @@
 using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
 
 namespace NexusReader.Domain.Entities;
 
@@ -11,6 +12,9 @@ public class SemanticKnowledgeCache
     [Required]
     public string JsonData { get; set; } = string.Empty;
 
+    [Required]
+    public string OriginalText { get; set; } = string.Empty;
+
     [Required]
     [MaxLength(50)]
     public string ModelId { get; set; } = "gemini-1.5-flash";
@@ -19,5 +23,12 @@ public class SemanticKnowledgeCache
     [MaxLength(10)]
     public string PromptVersion { get; set; } = "1.0";
 
+    [Required]
+    [MaxLength(128)]
+    public string TenantId { get; set; } = string.Empty;
+
+    [Column(TypeName = "vector(1536)")] // text-embedding-004 has 768 or 1536 dims, assuming 1536 for high-fidelity
+    public float[]? Vector { get; set; }
+
     public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
 }