claude: Fix remote fonts not recognised in brand extensions (#13685)

When a brand.yml file with remote font URLs (e.g., https://...) is
located in a subfolder (like _extensions/my-brand/), the font URL
was incorrectly joined with the path prefix, resulting in broken
paths like "_extensions/my-brand/https:/...".

Add isExternalPath helper to detect URLs and skip path joining for
external font paths.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: gordonwoodhull

src/core/sass/brand.ts

@@ -150,6 +150,8 @@ const googleFontImportString = (description: BrandFontGoogle) => {
   }:${styleString}wght@${weights}&display=${display}');`;
 };
 
+const isExternalPath = (path: string) => /^\w+:/.test(path);
+
 const fileFontImportString = (brand: Brand, description: BrandFontFile) => {
   const pathPrefix = relative(brand.projectDir, brand.brandDir);
   const parts = [];
@@ -162,9 +164,12 @@ const fileFontImportString = (brand: Brand, description: BrandFontFile) => {
       weight = file.weight;
       style = file.style;
     }
+    const fontUrl = isExternalPath(path)
+      ? path
+      : join(pathPrefix, path).replace(/\\/g, "/");
     parts.push(`@font-face {
     font-family: '${description.family}';
-    src: url('${join(pathPrefix, path).replace(/\\/g, "/")}');
+    src: url('${fontUrl}');
     font-weight: ${weight || "normal"};
     font-style: ${style || "normal"};
 }\n`);

tests/docs/smoke-all/brand/typography/remote-font-extension/.gitignore

@@ -0,0 +1,2 @@
+/.quarto/
+**/*.quarto_ipynb

tests/docs/smoke-all/brand/typography/remote-font-extension/_extensions/my-brand/_extension.yml

@@ -0,0 +1,8 @@
+title: My Brand
+author: Quarto
+version: 1.0.0
+quarto-required: ">=99.9.0"
+contributes:
+  metadata:
+    project:
+      brand: mybrand.yml

tests/docs/smoke-all/brand/typography/remote-font-extension/_extensions/my-brand/mybrand.yml

@@ -0,0 +1,8 @@
+typography:
+  fonts:
+    - family: Noto Sans
+      source: file
+      files:
+        - path: https://notofonts.github.io/latin-greek-cyrillic/fonts/NotoSans/unhinted/ttf/NotoSans-Regular.ttf
+  base:
+    family: Noto Sans

tests/docs/smoke-all/brand/typography/remote-font-extension/_quarto.yml

@@ -0,0 +1,5 @@
+project:
+  type: default
+format:
+  html:
+    theme: brand

tests/docs/smoke-all/brand/typography/remote-font-extension/remote-font-extension.qmd

@@ -0,0 +1,15 @@
+---
+title: Remote Font Extension Test
+_quarto:
+  tests:
+    html:
+      ensureCssRegexMatches:
+        - ['src:url\("https://notofonts\.github\.io/']
+        - ['_extensions/my-brand/https:']
+---
+
+# Remote Font Test
+
+This document tests that remote font URLs in brand extensions are handled correctly (issue #13685).
+
+{{< lipsum 1 >}}