- Refactored KnowledgeUnit to use Guid EbookId and added navigation property
- Updated AppDbContext with fluent configuration and cascade delete
- Propagated ebookId through IKnowledgeService and API endpoints
- Generated EF migration for schema changes

@@ -9,3 +8,1 @@
-    Task<Result<KnowledgePacket>> GetGraphDataAsync(string text, string tenantId, CancellationToken cancellationToken = default);
-    Task<Result<KnowledgePacket>> GetKnowledgeMapAsync(string text, string tenantId, CancellationToken cancellationToken = default);
-    Task<Result<KnowledgePacket>> GetSummaryAndQuizAsync(string text, string tenantId, CancellationToken cancellationToken = default);
+    Task<Result<KnowledgePacket>> GetKnowledgeAsync(string text, string tenantId, Guid? ebookId = null, CancellationToken cancellationToken = default);

@@ -14,3 +14,2 @@
     [Required]
-    [MaxLength(128)]
-    public string SourceId { get; set; } = string.Empty;
+    public Guid EbookId { get; set; }

@@ -211,0 +212,4 @@
+            // If not provided, we should ideally have a "Global" ebook or make it nullable.
+            // For now, we use Guid.Empty which will likely fail FK if not present,
+            // or we make the property nullable in the entity.
+            unit.EbookId = ebookId ?? Guid.Empty;