fix(data): enable foreign_keys pragma in MigrateAndConfigure

src/ClaudeDo.Data/ClaudeDoDbContext.cs

@@ -45,6 +45,13 @@ public class ClaudeDoDbContext : DbContext
                 walCmd.ExecuteNonQuery();
             }
 
+            // Enable FK enforcement — SQLite defaults to OFF per connection.
+            using (var fkCmd = conn.CreateCommand())
+            {
+                fkCmd.CommandText = "PRAGMA foreign_keys=ON;";
+                fkCmd.ExecuteNonQuery();
+            }
+
             // If the 'lists' table exists but __EFMigrationsHistory does not,
             // this is a pre-EF database. Baseline the InitialCreate migration.
             using (var cmd = conn.CreateCommand())