Sync lockfile pdfjs-dist specifier to exact 5.4.296

CI's pnpm install --frozen-lockfile rejected the previous commit because
package.json was edited to drop the caret but the lockfile still had
^5.4.296. Regenerate so specifiers match.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pnpm-lock.yaml

@@ -160,7 +160,7 @@ importers:
         specifier: ^1.8.0
         version: 1.8.0(react@19.2.5)
       pdfjs-dist:
-        specifier: ^5.4.296
+        specifier: 5.4.296
         version: 5.4.296
       react:
         specifier: ^19.2.4