fix(response-viewer): open markdown links to file paths in the preview, not as a same-origin URL

Codex cites files as [label](/abs/path). The chat view gave those links target=_blank, so a click opened <origin>/abs/path and landed on a Fastify 404. Path-shaped hrefs now take the linkified-path shape the file preview already opens; scheme, protocol-relative and fragment links are unchanged.

docs/wiki/Mobile-Guide.md

@@ -134,8 +134,9 @@ already writing in the editor.
 - **Tap a link** in terminal output and it opens in a new tab. Same for a link in an agent's
   answer in the response viewer — it opens a tab rather than navigating the dashboard away,
   which on a phone would unload the whole session view.
-- **Tap a file path** an agent printed and the file-preview overlay opens (Markdown rendered,
-  HTML as a page); a log or other plain-text path opens the log viewer. Works in scrolled-up
+- **Tap a file path** an agent printed, or a link to one in its answer (Codex writes
+  `[report](/tmp/report.json)`), and the file-preview overlay opens (Markdown rendered, HTML
+  as a page); a log or other plain-text path opens the log viewer. Works in scrolled-up
   transcript too.
 - A tap on the prose *beside* a link still places the cursor as usual, and a tap on a dialog's
   numbered choice still answers the dialog even when the row contains a path — the dialog wins,

docs/wiki/Working-With-Files.md

@@ -84,7 +84,8 @@ File paths in a session are links. That works in two places:
 
 - **In the terminal**, on any absolute path an agent prints.
 - **In the response viewer**, where paths are usually written as prose or in backticks. They
-  render as underlined monospace links.
+  render as underlined monospace links. A Markdown link whose target is a path
+  (`[report](/tmp/run/report.json)`, the way Codex cites files) opens the same way.
 
 Clicking one opens it in the preview: images and PDFs render, video and audio play with a
 working scrub bar, documents convert, text shows inline, Markdown renders and HTML opens as a