Merge 'fix: update changes() and total_changes() inside explicit transactions' from Damian Melia

### Issue
`changes()` and `total_changes()` were wrong inside explicit
`BEGIN...COMMIT` transactions (returning 0 or stale values). The non-
autocommit halt path in the VDBE never called `set_changes()`.
### Fix
Call `set_changes()` in the non-autocommit halt path when
`change_cnt_on` is true, so behavior matches SQLite.
### Testing
Regression tests added for both reproducers (DELETE in transaction and
INSERT with prior data), plus tests for `total_changes()` in
transactions.
#5146
I used AI to help me understand a bit more about the structure of the
tests and to help translate the linked production / reported error cases
into tests.

Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>

Closes #5437

Author: jussisaurio

core/vdbe/execute.rs

@@ -2051,6 +2051,11 @@ pub fn halt(
         if let Some(cdc_info) = state.pending_cdc_info.take() {
             program.connection.set_capture_data_changes_info(cdc_info);
         }
+        if program.change_cnt_on {
+            program
+                .connection
+                .set_changes(state.n_change.load(Ordering::SeqCst));
+        }
         Ok(InsnFunctionStepResult::Done)
     }
 }

testing/runner/tests/changes.sqltest

@@ -149,3 +149,75 @@ expect {
     1
 }
 
+test changes-insert-in-transaction {
+    create table t(id integer primary key, val text);
+    begin;
+    insert into t values(1, 'a'), (2, 'b'), (3, 'c');
+    select changes();
+    commit;
+}
+expect {
+    3
+}
+
+test changes-insert-in-transaction-after-commit {
+    create table t(id integer primary key, val text);
+    begin;
+    insert into t values(1, 'a'), (2, 'b'), (3, 'c');
+    commit;
+    select changes();
+}
+expect {
+    3
+}
+
+test changes-delete-in-transaction {
+    create table t(id integer primary key, val integer);
+    insert into t values(1, 10), (2, 20), (3, 30);
+    begin;
+    delete from t where val > 15;
+    select changes();
+    commit;
+}
+expect {
+    2
+}
+
+test changes-insert-in-transaction-with-prior-data {
+    create table t(id integer primary key, val integer);
+    insert into t values(1, 10), (2, 20), (3, 30);
+    begin;
+    insert into t values(4, 40), (5, 50);
+    select changes();
+    commit;
+}
+expect {
+    2
+}
+
+test changes-update-in-transaction {
+    create table t(id integer primary key, val text);
+    insert into t values(1, 'a'), (2, 'b'), (3, 'c');
+    begin;
+    update t set val = 'z' where id <= 2;
+    select changes();
+    commit;
+}
+expect {
+    2
+}
+
+test changes-multiple-stmts-in-transaction {
+    create table t(id integer primary key, val text);
+    begin;
+    insert into t values(1, 'a'), (2, 'b');
+    select changes();
+    insert into t values(3, 'c');
+    select changes();
+    commit;
+}
+expect {
+    2
+    1
+}
+

testing/runner/tests/total-changes.sqltest

@@ -58,3 +58,38 @@ expect {
     2
 }
 
+test total-changes-insert-in-transaction {
+    create table t(id integer primary key, val text);
+    begin;
+    insert into t values(1, 'a'), (2, 'b'), (3, 'c');
+    select total_changes();
+    commit;
+}
+expect {
+    3
+}
+
+test total-changes-insert-in-transaction-after-commit {
+    create table t(id integer primary key, val text);
+    begin;
+    insert into t values(1, 'a'), (2, 'b'), (3, 'c');
+    commit;
+    select total_changes();
+}
+expect {
+    3
+}
+
+test total-changes-multiple-stmts-in-transaction {
+    create table t(id integer primary key, val text);
+    insert into t values(1, 'a'), (2, 'b');
+    begin;
+    insert into t values(3, 'c');
+    delete from t where id = 1;
+    select total_changes();
+    commit;
+}
+expect {
+    4
+}
+