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

tests/BeforeAfter.Tests/BeforeTests.cs

@@ -358,7 +358,8 @@ public class BeforeTests
     }
 
     // ---------------------------------------------------------------------
-    // (18) DbBase.FindRequired<T> throws when no match is found.
+    // (18) DbBase.FindRequired<T> throws ObjectNotFoundException when no match
+    //       is found (the domain-specific lookup miss, not a BCL exception).
     // ---------------------------------------------------------------------
     [Fact]
     public void DbBase_FindRequired_T_throws_when_no_match()
@@ -366,7 +367,7 @@ public class BeforeTests
         var db = new DbContext();
         db.Attach(new Client { Name = "Acme" });
 
-        var ex = Assert.Throws<InvalidOperationException>(() =>
+        var ex = Assert.Throws<ObjectNotFoundException>(() =>
             DbBase.FindRequired<Client>(c => c.Name == "Nobody", db, "name == Nobody"));
 
         Assert.Contains("Nobody", ex.Message);
@@ -376,6 +377,9 @@ public class BeforeTests
     // ---------------------------------------------------------------------
     // (19) DbBase.FindRequired<T> throws with a useful message when no context is
     //       configured (both explicit null and singleton null).
+    //
+    //       Deliberately InvalidOperationException, not ObjectNotFoundException:
+    //       a missing context is a configuration error, not a lookup miss.
     // ---------------------------------------------------------------------
     [Fact]
     public void DbBase_FindRequired_T_throws_when_no_context_configured()
@@ -405,7 +409,8 @@ public class BeforeTests
     }
 
     // ---------------------------------------------------------------------
-    // (21) Client.FindByNameRequired throws when no match — message includes name.
+    // (21) Client.FindByNameRequired throws ObjectNotFoundException when no
+    //       match — message includes name.
     // ---------------------------------------------------------------------
     [Fact]
     public void Client_FindByNameRequired_throws_with_name_when_not_found()
@@ -413,7 +418,7 @@ public class BeforeTests
         var db = new DbContext();
         db.Attach(new Client { Name = "Acme Corp" });
 
-        var ex = Assert.Throws<InvalidOperationException>(() =>
+        var ex = Assert.Throws<ObjectNotFoundException>(() =>
             Client.FindByNameRequired("Nobody", db));
 
         Assert.Contains("Nobody", ex.Message);
@@ -445,6 +450,7 @@ public class BeforeTests
     // ---------------------------------------------------------------------
     // (23) Client.FindByNameRequired throws with a useful message when the
     //       singleton is not configured (no arg, no singleton).
+    //       Stays InvalidOperationException: configuration error, not a miss.
     // ---------------------------------------------------------------------
     [Fact]
     public void Client_FindByNameRequired_throws_with_context_hint_when_singleton_null()