Update PHP version to 8.4 and add property hooks

app/context.php

@@ -0,0 +1,41 @@
+<?php
+
+readonly class Templates {
+    public function __construct(
+        public string $base,
+        public string $page,
+        public string $list
+    ) {}
+}
+
+class Context {
+    // Use asymmetric visibility for immutability (PHP 8.4)
+    public function __construct(
+        public private(set) string $contentDir,
+        public private(set) string $currentLang,
+        public private(set) string $defaultLang,
+        public private(set) array $availableLangs,
+        public private(set) Templates $templates,
+        public private(set) string $requestPath,
+        public private(set) bool $hasTrailingSlash
+    ) {}
+    
+    // Property hooks - computed properties (PHP 8.4)
+    public string $langPrefix {
+        get => $this->currentLang !== $this->defaultLang 
+            ? "/{$this->currentLang}" 
+            : '';
+    }
+    
+    public array $navigation {
+        get => buildNavigation($this);
+    }
+    
+    public string $homeLabel {
+        get => loadMetadata($this->contentDir, $this->currentLang, $this->defaultLang)['slug'] ?? 'Home';
+    }
+    
+    public array $translations {
+        get => loadTranslations($this->currentLang);
+    }
+}