Fix silent no-op in Queue::addJob when task does not queue a job

[dereuromark]

Problem

The admin UI has a "Trigger Jobs" panel that lets operators add demo jobs via Queue::addJob(). For tasks implementing AddInterface, the action calls $object->add(null) and then unconditionally shows $this->Flash->success('Job X added').

But add() returns void. Some tasks silently do nothing when required configuration is missing. The canonical case is EmailTask::add():

public function add(?string $data): void {
    $adminEmail = Configure::read('Config.adminEmail');
    if ($adminEmail) {
        $this->QueuedJobs->createJob('Queue.Email', $data);
        $this->io->success('OK, job created for email ...');
        return;
    }
    $this->io->warn('Queue Email Task cannot be added via Console without `Config.adminEmail` being set.');
    // ... more $this->io->out() that go to ConsoleIo (invisible in web context)
}

When Config.adminEmail is not set:

• add() writes a warning via $this->io (ConsoleIo — invisible in a web request)
• no job is created
• the controller still shows a green success flash

Result: the operator sees "Job Queue.Email added" but no row appears in the queue. Very confusing to debug.

Fix

Measure the QueuedJobs count before and after invoking the task. If the count didn't change, show an error flash instead of a success flash — and point the operator at the likely config gap.

+$before = $this->QueuedJobs->find()->count();
 if ($object instanceof AddInterface) {
     $object->add(null);
 } else {
     $this->QueuedJobs->createJob($job);
 }
+$after = $this->QueuedJobs->find()->count();

-$this->Flash->success('Job ' . $job . ' added');
+if ($after > $before) {
+    $this->Flash->success('Job ' . $job . ' added');
+} else {
+    $this->Flash->error(
+        'Job ' . $job . ' could not be added — the task did not create a job. '
+        . 'Check configuration (e.g. Config.adminEmail for Queue.Email) and server logs.',
+    );
+}

This keeps AddInterface::add() non-breaking (still void). It's a small count delta check that handles any future task with similar silent-no-op behavior.

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 50.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.14%. Comparing base (5410512) to head (7a7e7f6).

Files with missing lines	Patch %	Lines
src/Controller/Admin/QueueController.php	50.00%	4 Missing ⚠️
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Additional details and impacted files

@@             Coverage Diff              @@
##             master     #478      +/-   ##
============================================
- Coverage     77.22%   77.14%   -0.08%     
- Complexity      949      950       +1     
============================================
  Files            45       45              
  Lines          3196     3216      +20     
============================================
+ Hits           2468     2481      +13     
- Misses          728      735       +7     

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