Throw ObjectNotFoundException from FindRequired; add run-console wrappers

- DbBase.FindRequired / Client.FindByNameRequired now throw the
  domain-specific ObjectNotFoundException (NHibernate lineage; Rails
  equivalent: ActiveRecord::RecordNotFound) on a lookup miss; the
  no-context case stays InvalidOperationException (configuration error)
- Console demo catches the new type; tests (18)/(21) assert it,
  (19)/(23) keep InvalidOperationException with rationale comments
- scripts/run-console.sh delegates to dotnet.sh; run-console.ps1 is
  the Windows/PowerShell counterpart (mise-first, repo-root cd)

Yak: objectnotfoundexception-run-console-wrappers-3p8b

src/Before.Console/Program.cs

@@ -44,9 +44,6 @@ foreach (var client in DbBase.Context!.Tracked.OfType<Client>())
 // ----- find by name -------------------------------------------------------
 Console.WriteLine("\n=== Find by Name (null-returning) ===");
 // No context argument: FindByName falls back to the DbBase.Context singleton.
-// This is the ActiveRecord ergonomic — call sites don't carry the context,
-// but the null that comes back on a miss can't tell "no such client" from
-// "nobody configured the context".
 var found = Client.FindByName("Jane Doe");
 if (found is not null)
 {
@@ -66,7 +63,7 @@ try
     Console.WriteLine($"Found: {required.Name} [{required.Id}]");
     Console.WriteLine($"  Orders: {required.Orders.Count}");
 }
-catch (InvalidOperationException ex)
+catch (ObjectNotFoundException ex)
 {
     Console.WriteLine($"Not found: {ex.Message}");
 }
@@ -79,7 +76,7 @@ try
 {
     Client.FindByNameRequired("Nobody Here");
 }
-catch (InvalidOperationException ex)
+catch (ObjectNotFoundException ex)
 {
     var msg = ex.Message.ReplaceLineEndings(" ").Trim();
     Console.WriteLine($"FindByNameRequired(\"Nobody Here\"): throws - {msg}");