feat: project skeleton with Config and exceptions

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

tests/ConfigTest.php

@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Weerscherm\Tests;
+
+use PHPUnit\Framework\TestCase;
+use Weerscherm\Config;
+
+final class ConfigTest extends TestCase
+{
+    private string $file;
+
+    protected function setUp(): void
+    {
+        $this->file = tempnam(sys_get_temp_dir(), 'cfg');
+    }
+
+    protected function tearDown(): void
+    {
+        @unlink($this->file);
+    }
+
+    public function testDefaultsApplyWhenKeysAreMissing(): void
+    {
+        file_put_contents($this->file, '<?php return [];');
+        $config = Config::load($this->file);
+
+        self::assertSame('Europe/Berlin', $config->get('timezone'));
+        self::assertSame('fixture', $config->get('data_source'));
+        self::assertSame(['stations' => 300, 'measure' => 900, 'forecast' => 3600], $config->get('cache_ttl'));
+        self::assertSame([], $config->get('indoor_modules'));
+        self::assertNull($config->get('netatmo_device_id'));
+    }
+
+    public function testFileValuesOverrideDefaults(): void
+    {
+        file_put_contents($this->file, '<?php return ["timezone" => "Europe/Amsterdam", "cache_ttl" => ["stations" => 60]];');
+        $config = Config::load($this->file);
+
+        self::assertSame('Europe/Amsterdam', $config->get('timezone'));
+        self::assertSame(['stations' => 60, 'measure' => 900, 'forecast' => 3600], $config->get('cache_ttl'));
+    }
+
+    public function testUnknownKeyReturnsGivenDefault(): void
+    {
+        file_put_contents($this->file, '<?php return [];');
+        self::assertSame('x', Config::load($this->file)->get('nope', 'x'));
+    }
+
+    public function testFileMustReturnArray(): void
+    {
+        file_put_contents($this->file, '<?php return "nee";');
+        $this->expectException(\RuntimeException::class);
+        Config::load($this->file);
+    }
+}