Replace v1 with v2 codebase

Full rewrite: swap out the v1 framework (src/, controllers/, views/,
twig/, sass/, skeleton/) for the working v2 codebase from phpproject
(App/, novaconium/, public/).

public/router.php

@@ -0,0 +1,23 @@
+<?php
+// Dev-only router for `php -S`, mimicking the .htaccess rules for local testing.
+// Not used in production (Apache reads .htaccess directly).
+
+$uri = urldecode(parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH));
+
+if ($uri !== '/' && str_ends_with($uri, '/')) {
+    header('Location: ' . rtrim($uri, '/'), true, 301);
+    exit;
+}
+
+$file = __DIR__ . $uri;
+if ($uri !== '/' && (is_file($file) || is_dir($file))) {
+    return false; // let the built-in server handle real files/dirs (css, cache)
+}
+
+$cacheFile = __DIR__ . '/cache' . $uri . '/index.html';
+if (is_file($cacheFile)) {
+    readfile($cacheFile);
+    return true;
+}
+
+require __DIR__ . '/index.php';