Add breadcrumbs function, docs and tests

devel/tests/helpers/build_breadcrumbs_skips_missing_dirs.phpt

@@ -0,0 +1,39 @@
+--TEST--
+buildBreadcrumbs: skips non-existent directories gracefully
+--FILE--
+<?php
+require '/var/www/app/context.php';
+require '/var/www/app/hooks.php';
+require '/var/www/app/constants.php';
+require '/var/www/app/helpers.php';
+require '/var/www/app/content.php';
+
+// Create temp directory structure with only level 1
+$tempBase = sys_get_temp_dir() . '/phpt_' . getmypid();
+$tempContent = $tempBase . '/content';
+$tempLevel1 = $tempContent . '/nyheter';
+
+mkdir($tempLevel1, 0777, true);
+file_put_contents($tempLevel1 . '/metadata.ini', "title = Nyheter\n");
+
+// Request path has middle directories that don't exist
+$ctx = new Context(
+    contentDir: $tempContent,
+    templates: new Templates('/tmp/base.php', '/tmp/page.php', '/tmp/list.php'),
+    requestPath: 'nyheter/nonexistent/artikkel',
+    hasTrailingSlash: false
+);
+
+$result = buildBreadcrumbs($ctx);
+
+// Only nyheter exists, so only 1 breadcrumb
+echo count($result) . "\n";
+
+// Cleanup
+unlink($tempLevel1 . '/metadata.ini');
+rmdir($tempLevel1);
+rmdir($tempContent);
+rmdir($tempBase);
+?>
+--EXPECT--
+1