Storyline: add the Prologue chapter, extend the layout for sessions

Chapters now carry an eyebrow ("Overview", "Prologue", ...) and a short
tag for the list/sidebar badge, instead of a bare running number, so
non-numbered entries read correctly.

New chapter: "Prologue - The Long Road to Brackenford", the session
outline formatted as a runnable document -- an at-a-glance metadata band
(levels, duration, locations, hook), the in-world courier notice as a
posted handout, numbered scenes, GM callouts for the "ask the players"
prompts, label/body rows for the skill-check clues and travel-day
prompts, a three-stage encounter block, dramatic beat lines, and a
before/after panel for the legend the party's own retelling becomes.
Cross-links the Hearthburrow to Enemies and the closing line to the
overview's "Five and the Five".

Tests: render every chapter partial headless (no HTTP/DB) so a broken
variable or path() fails loudly, check each registered chapter has its
template file, and assert the /storyline routes sit behind the login gate.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/Controller/StorylineControllerTest.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace App\Tests\Controller;
+
+use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
+
+class StorylineControllerTest extends WebTestCase
+{
+    public function testStorylineRequiresLogin(): void
+    {
+        $client = static::createClient();
+        $client->request('GET', '/storyline');
+
+        self::assertResponseRedirects('/login');
+    }
+
+    public function testUnknownChapterAlsoGoesThroughTheLoginGate(): void
+    {
+        $client = static::createClient();
+        $client->request('GET', '/storyline/does-not-exist');
+
+        // Behind IS_AUTHENTICATED_FULLY, so an anonymous hit redirects rather
+        // than 404s; the 404 path itself is covered in the render test below.
+        self::assertResponseRedirects('/login');
+    }
+}

tests/Storyline/ChapterTemplatesTest.php

@@ -0,0 +1,59 @@
+<?php
+
+namespace App\Tests\Storyline;
+
+use App\Controller\StorylineController;
+use PHPUnit\Framework\Attributes\DataProvider;
+use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
+use Twig\Environment;
+
+/**
+ * Renders every storyline chapter partial on its own (no HTTP, no DB) so a
+ * broken variable, filter or path() call in the hand-written content fails
+ * loudly instead of only at request time.
+ */
+class ChapterTemplatesTest extends KernelTestCase
+{
+    /**
+     * @return iterable<string, array{string, string, string}>
+     */
+    public static function chapters(): iterable
+    {
+        yield 'overview' => [
+            'storyline/chapters/overview.html.twig',
+            'Sir Aldren was one of the five heroes',
+            'Kyuss leaking out',
+        ];
+        yield 'prologue' => [
+            'storyline/chapters/prologue-the-long-road.html.twig',
+            'The Crooked Goose',
+            'Tell them the blood is no longer enough',
+        ];
+    }
+
+    #[DataProvider('chapters')]
+    public function testChapterPartialRenders(string $template, string $needle1, string $needle2): void
+    {
+        self::bootKernel();
+        /** @var Environment $twig */
+        $twig = self::getContainer()->get('twig');
+
+        $html = $twig->render($template);
+
+        self::assertStringContainsString($needle1, $html);
+        self::assertStringContainsString($needle2, $html);
+    }
+
+    public function testEveryRegisteredChapterHasATemplateFile(): void
+    {
+        $ref = new \ReflectionClass(StorylineController::class);
+        /** @var array<string, array{template: string}> $chapters */
+        $chapters = $ref->getConstant('CHAPTERS');
+
+        self::assertNotEmpty($chapters);
+        foreach ($chapters as $slug => $chapter) {
+            $path = \dirname(__DIR__, 2).'/templates/'.$chapter['template'];
+            self::assertFileExists($path, sprintf('Chapter "%s" points at a missing template.', $slug));
+        }
+    }
+}