Add robust release update and API health checks

This commit introduces a release update mechanism, including candidate detection, asset pre-downloading, and installation workflows with proper state management. Additionally, it implements API health checks both for successful and failure scenarios and adds related unit and e2e tests for enhanced reliability.

services/nginx/app/modules/selfserve/classes/selfserve_wash_flow.php

@@ -2408,11 +2408,20 @@ class selfserve_wash_flow implements selfserve_wash_flow_i
 
     protected function taskUsesProgramPicker(array $task): bool
     {
-        return in_array(
+        if (in_array(
             'PROGRAM_PICKER',
             $this->normalizeServiceNames($this->normalizeJsonArray($task['services'] ?? null)),
             true
-        );
+        )) {
+            return true;
+        }
+
+        return in_array('program_picker', $this->normalizeButtonList($task['buttons'] ?? null), true);
+    }
+
+    protected function isProgramNumberButton(mixed $button): bool
+    {
+        return is_int($button) && $button >= 0 && $button <= 11;
     }
 
     protected function dynamicImageButtonSequenceForTask(array $task): array
@@ -2422,7 +2431,15 @@ class selfserve_wash_flow implements selfserve_wash_flow_i
             return $buttons;
         }
 
-        return $this->normalizeButtonList(array_merge(['program_picker'], $buttons));
+        $sequence = ['program_picker'];
+        foreach ($buttons as $button) {
+            if ($button === 'program_picker' || $this->isProgramNumberButton($button)) {
+                continue;
+            }
+            $sequence[] = $button;
+        }
+
+        return $this->normalizeButtonList($sequence);
     }
 
     /**