refactor: standardize SQLiteConnection disposal via using; guard config

Replace the try/finally { connection.Close(); } pattern used across
most of DataAccess.cs with using declarations, so disposal happens
automatically and can't be skipped by a future edit that adds an
early return before the finally. Left the shared-connection
(ownsConnection) call sites alone since those intentionally outlive
a single method call.

Also drop a stray unused `using static ... JSType` import, and make
a missing ContainsList config setting fail with a clear
InvalidOperationException instead of a NullReferenceException from
Split(',') on null.

URLNotesGrabberCORE/Program.cs

@@ -5,7 +5,6 @@ using Microsoft.Extensions.Configuration;
 using System.Configuration;
 using System.Threading;
 using Microsoft.Extensions.Diagnostics.Latency;
-using static System.Runtime.InteropServices.JavaScript.JSType;
 using System.Text.RegularExpressions;
 
 namespace URLNotesGrabberCORE
@@ -140,7 +139,10 @@ namespace URLNotesGrabberCORE
                 Console.SetOut(dualLogger);
             }
 
-            List<string> contains = settings.GetValue<string>("ContainsList").Split(',').ToList();
+            string? containsListSetting = settings.GetValue<string>("ContainsList");
+            if (string.IsNullOrEmpty(containsListSetting))
+                throw new InvalidOperationException("ContainsList is not configured in appsettings.json");
+            List<string> contains = containsListSetting.Split(',').ToList();
             bool logTraversalRecordImports = settings.GetValue("LogTraversalRecordImports", false);
 
             if (args.Length == 0) //Traverse folder structure to add posts and thus blogs to DB