fix(files): open file paths agents print, from the terminal and the chat

A path an agent prints was already underlined in the terminal, but clicking
one opened the preview overlay on "File not found": file-content/file-raw
resolve against the session workingDir and refuse anything outside it, and the
paths agents print most (a /tmp capture, Claude's own scratchpad, another
checkout) are outside it by definition. In the response viewer those paths were
not links at all.

- openFilePreview() detects an out-of-workspace path and registers it through
  POST /api/sessions/:id/attachments first, rendering by attachment id. That is
  the surface built for live external files, so the server-side guard is
  unchanged: secret trees blocked, symlinks resolved, extension allowlist. The
  workspace routes keep refusing escapes exactly as before.
- New optional `notify` field on that route. `notify: false` suppresses only the
  attachment:detected broadcast, so a click does not also pop a card announcing
  the file already filling the screen. Default stays true for the CLI and
  publish callers.
- _linkifyFilePaths() links paths in rendered response-viewer markdown. It walks
  text nodes and builds anchors with DOM APIs (the source is model output; never
  a string rebuild of sanitized markup), skips subtrees already inside an <a>,
  and keeps the message text byte-identical so copy-code is unaffected.
- One path pattern in constants.js now feeds both the xterm link provider and
  the chat linkifier, a fresh instance per call since lastIndex is per-object
  state. It picks up /Users and /mnt roots (nothing was clickable on macOS or
  WSL), plus docx/pptx and video/audio extensions.
- .file-preview-overlay moves to z-index 5100, above the response viewer at
  5000. At its old 2000 a path clicked in the chat opened the overlay behind the
  panel it was launched from.

Verified end to end on an isolated instance, desktop and phone viewport: real
clicks in the terminal and the chat both render the image, external md and pdf
render, /etc/hosts is still refused, workspace previews unchanged.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/web/public/terminal-ui.js

@@ -1423,19 +1423,19 @@ Object.assign(CodemanApp.prototype, {
         // the whole tab on hover. Non-empty token + bounded reps is O(n).
         const cmdPattern = /\b(tail|cat|head|less|grep|watch|vim|nano)\s+(?:[^\s\/]+\s+){0,4}(\/[^\s"'<>|;&\n\x00-\x1f]+)/g;
 
-        // Pattern 2: Paths with common extensions.
-        // Image/PDF extensions are included so pasted-attachment paths
-        // (`.claude-images/paste-*.png`) are clickable; they open the file preview
-        // rather than the log viewer (see addLink).
-        const extPattern =
-          /(\/(?:home|tmp|var|etc|opt)[^\s"'<>|;&\n\x00-\x1f]*\.(?:log|txt|json|md|yaml|yml|csv|xml|sh|py|ts|js|png|jpe?g|gif|webp|bmp|svg|pdf))\b/g;
+        // Pattern 2: Paths with common extensions. Image/PDF/media extensions are
+        // included so pasted-attachment paths (`.claude-images/paste-*.png`) and
+        // screenshots an agent just wrote are clickable; those open the file
+        // preview rather than the log viewer (see addLink).
+        //
+        // The literal lives in constants.js because the response viewer linkifies
+        // the SAME paths out of markdown — one definition, two consumers. A fresh
+        // instance per call: `lastIndex` is per-object state.
+        const extPattern = absoluteFilePathPattern();
 
         // Pattern 3: Bash() tool output
         const bashPattern = /Bash\([^)]*?(\/(?:home|tmp|var|etc|opt)[^\s"'<>|;&\)\n\x00-\x1f]+)/g;
 
-        /** Extensions that should open the image/document preview, not the log viewer. */
-        const PREVIEW_EXTS = new Set(['png', 'jpg', 'jpeg', 'gif', 'webp', 'bmp', 'svg', 'pdf']);
-
         const addLink = (filePath, matchIndex) => {
           const startCol = lineText.indexOf(filePath, matchIndex);
           if (startCol === -1) return;
@@ -1454,9 +1454,10 @@ Object.assign(CodemanApp.prototype, {
             },
             activate(event, text) {
               // Tailing a PNG in the log viewer shows binary noise; the file preview
-              // already renders images and PDFs inline.
-              const ext = (text.split('.').pop() || '').toLowerCase();
-              if (PREVIEW_EXTS.has(ext)) {
+              // already renders images, PDFs, documents and media inline — and it
+              // now reaches files outside the workspace too, which is where an
+              // agent's screenshots and scratchpad captures actually land.
+              if (previewsInFileViewer(text)) {
                 self.openFilePreview(text, self.activeSessionId);
                 return;
               }