Let plugins run their own PHP code

A plugin can now bring a plugin.php that registers hooks, scheduled tasks, its own tables, public pages and admin screens. Failures stay contained to the plugin; a form on a plugin page can be submitted.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/Ops/Scheduler.php

@@ -62,6 +62,7 @@ final class Scheduler
         private Connection $db,
         private iterable $tasks,
         private string $projectDir,
+        private ?\App\Plugin\PluginRuntime $plugins = null,
     ) {
     }
 
@@ -268,6 +269,14 @@ final class Scheduler
      * @return bool false, wenn die Tabelle (noch) nicht da ist - vor der Installation und
      *              zwischen hochgeladenem Code und ausgefuehrter Migration
      */
+    /** Nach dem Ein- oder Ausschalten eines Plugins: Der Plan kennt dessen Aufgaben sofort. */
+    public function pluginsChanged(): void
+    {
+        $this->registry = null;
+        $this->sync();
+        $this->refreshState();
+    }
+
     public function sync(?\DateTimeImmutable $now = null): bool
     {
         $now ??= self::now();
@@ -396,6 +405,9 @@ final class Scheduler
         foreach ($this->tasks as $task) {
             $registry[$task->name()] = $task;
         }
+        foreach ($this->plugins?->tasks() ?? [] as $task) {
+            $registry[$task->name()] = $task;
+        }
         ksort($registry);
 
         return $this->registry = $registry;