feat: add View Markdown button to doc pages

Adds a ViewMarkdown component that renders a "View Markdown" link button
next to "Edit this page" in the feedback section, surfacing the raw .md
URL that the markdownSource middleware already serves.

Author: donjo

_components/Feedback.tsx

@@ -1,4 +1,5 @@
 import EditThisPage from "./EditThisPage.tsx";
+import ViewMarkdown from "./ViewMarkdown.tsx";
 
 export default function Feedback({ file }: { file: string | undefined }) {
   if (!file) {
@@ -70,6 +71,7 @@ export default function Feedback({ file }: { file: string | undefined }) {
                     </svg>
                   </label>
                   {!file.includes("[") && <EditThisPage file={file} />}
+                  {!file.includes("[") && <ViewMarkdown file={file} />}
                 </div>
                 <div
                   id="feedback-more"

_components/ViewMarkdown.tsx

@@ -0,0 +1,21 @@
+export default function ViewMarkdown({ file }: { file: string | undefined }) {
+  if (!file) return null;
+
+  return (
+    <a class="btn" target="_blank" href={file}>
+      View Markdown
+      <svg
+        xmlns="http://www.w3.org/2000/svg"
+        aria-hidden="true"
+        focusable="false"
+        fill="currentColor"
+        width="16"
+        height="16"
+        viewBox="0 0 16 16"
+        style="display:inline-block;user-select:none;vertical-align:text-bottom;"
+      >
+        <path d="M2 1.75C2 .784 2.784 0 3.75 0h6.586c.464 0 .909.184 1.237.513l2.914 2.914c.329.328.513.773.513 1.237v9.586A1.75 1.75 0 0 1 13.25 16h-9.5A1.75 1.75 0 0 1 2 14.25Zm1.75-.25a.25.25 0 0 0-.25.25v12.5c0 .138.112.25.25.25h9.5a.25.25 0 0 0 .25-.25V6h-2.75A1.75 1.75 0 0 1 9 4.25V1.5Zm6.75.062V4.25c0 .138.112.25.25.25h2.688l-.011-.013-2.914-2.914-.013-.011Z" />
+      </svg>
+    </a>
+  );
+}