Bug 41603: Move after_hold_action plugin hook outside transaction

The after_hold_action plugin hook is currently called from within the
hold cancellation transaction in Koha::Hold->cancel(). This creates
a fragile architecture where any plugin performing database queries
can cause lock timeouts and transaction failures.

The issue manifests when plugins query tables with foreign key
relationships to biblio records. Even lightweight queries on seemingly
unrelated tables (like illrequests) can trigger lock conflicts due to
foreign key constraints that require shared locks on referenced rows.

Since the plugin hook executes while the transaction holds locks on
reserves/biblio tables, any plugin database access creates potential
for circular lock dependencies and timeouts.

This patch moves the plugin hook call outside the transaction boundary,
ensuring that:
- Core hold operations complete without plugin interference
- Plugins receive the same data but execute after transaction commit
- Database lock conflicts are eliminated
- Plugin failures cannot corrupt core hold cancellation logic

The hook receives identical data through a stored reference to the
cancelled hold, maintaining full backward compatibility while
eliminating the transaction fragility.

Test plan:
1. Install any plugin that implements after_hold_action hook with
   database queries (e.g., ILL plugins checking hold relationships)
2. Create a hold and attempt to cancel it
3. Without patch: Operation may timeout with "Lock wait timeout exceeded"
4. With patch: Operation completes immediately
5. Verify plugin hook still receives correct hold data

Signed-off-by: Tomás Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@openfifth.co.uk>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>

Koha/Hold.pm

@@ -860,6 +860,9 @@ sub cancel {
 
     my $autofill_next = $params->{autofill} && $self->itemnumber && $self->found && $self->found eq 'W';
 
+    # Store hold data for plugin hook (before transaction)
+    my $old_hold_data;
+
     my $original = C4::Context->preference('HoldsLog') ? $self->unblessed : undef;
 
     $self->_result->result_source->schema->txn_do(
@@ -916,13 +919,8 @@ sub cancel {
 
             my $old_me = $self->_move_to_old;
 
-            Koha::Plugins->call(
-                'after_hold_action',
-                {
-                    action  => 'cancel',
-                    payload => { hold => $old_me->get_from_storage }
-                }
-            );
+            # Store data for plugin hook (to be called after transaction)
+            $old_hold_data = $old_me->get_from_storage;
 
             # anonymize if required
             $old_me->anonymize
@@ -966,6 +964,15 @@ sub cancel {
         }
     );
 
+    # Call plugin hook AFTER transaction completes
+    Koha::Plugins->call(
+        'after_hold_action',
+        {
+            action  => 'cancel',
+            payload => { hold => $old_hold_data }
+        }
+    );
+
     $self->cleanup_hold_group() unless $params->{skip_hold_group_cleanup};
 
     if ($autofill_next) {