Move files, complete PHP migration

The application works the same way as the F# version

src/lib/Domain/History.php

@@ -0,0 +1,25 @@
+<?php declare(strict_types=1);
+
+namespace MyPrayerJournal\Domain;
+
+use JsonSerializable;
+
+/**
+ * A record of an action taken on a request
+ */
+class History implements JsonSerializable
+{
+    /**
+     * @param string $asOf The date/time this entry was made
+     * @param RequestAction $action The action taken for this history entry
+     * @param string|null $text The text for this history entry (optional)
+     */
+    public function __construct(public string $asOf, public RequestAction $action, public ?string $text = null) { }
+
+    public function jsonSerialize(): mixed
+    {
+        $values = ['asOf' => $this->asOf, 'action' => $this->action->value];
+        if (isset($this->text)) $values['text'] = $this->text;
+        return $values;
+    }
+}