Scaffold ProjectZomboid game stubs

Add empty per-component subdirectories under src/{Analyser,Log,Parser,Pattern}/ProjectZomboid/
with .gitkeep markers, plus ProjectZomboidDetective stub extending the base Detective with
a TODO body. Smoke test under test/tests/Games/ProjectZomboid/ asserts the detective is
instantiable.

src/Detective/ProjectZomboid/ProjectZomboidDetective.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace IndifferentKetchup\Codex\Detective\ProjectZomboid;
+
+use IndifferentKetchup\Codex\Detective\Detective;
+
+class ProjectZomboidDetective extends Detective
+{
+    // TODO: implement game-specific log type detection
+}

test/tests/Games/ProjectZomboid/SmokeTest.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace IndifferentKetchup\Codex\Test\Tests\Games\ProjectZomboid;
+
+use IndifferentKetchup\Codex\Detective\ProjectZomboid\ProjectZomboidDetective;
+use PHPUnit\Framework\TestCase;
+
+class SmokeTest extends TestCase
+{
+    public function testDetectiveIsInstantiable(): void
+    {
+        $detective = new ProjectZomboidDetective();
+        $this->assertInstanceOf(ProjectZomboidDetective::class, $detective);
+    }
+}