Fix: rename Data/ to Database/ to avoid gitignore collision

.gitignore has '/data' which Windows git (case-insensitive) silently
matched '/Data/', so AppDbContext.cs was never committed and the Docker
build (Linux, case-sensitive) failed with CS0234 'Data' not found.
Renaming the directory to 'Database/' sidesteps the collision.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Services/ContentService.cs

@@ -1,6 +1,6 @@
 using System.Text.Json;
 using System.Text.Json.Nodes;
-using SoroushAsadi.Data;
+using SoroushAsadi.Database;
 
 namespace SoroushAsadi.Services;