paper + assignment: add PDF metadata via pdfmanagement-testphase

memoir is not yet compatible with the LaTeX tagged-PDF code, so full
\DocumentMetadata (which pulls in all the latex-lab tagging machinery)
crashes at compile time. Use \RequirePackage{pdfmanagement-testphase}
plus \DeclareDocumentMetadata to get the PDF-management layer — document
language, PDF 2.0 — without triggering tagging. Also adds pdflang and
pdfdisplaydoctitle to the existing hypersetup.

The \DocumentMetadata block and tagpdf load are left in the file as
commented-out lines so this is a one-edit swap once memoir gains
tagging support upstream:

    https://github.com/latex3/tagging-project/issues/910

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

paper_template/text.tex

@@ -1,6 +1,21 @@
+% memoir is currently incompatible with the LaTeX tagged-PDF code, so we
+% load just the PDF management layer (for metadata). When memoir support
+% lands upstream, swap this block for the commented-out \DocumentMetadata +
+% tagpdf lines below. See https://github.com/latex3/tagging-project/issues/910
+\RequirePackage{pdfmanagement-testphase}
+\DeclareDocumentMetadata{lang=en-US,pdfversion=2.0}
+
+% \DocumentMetadata{
+%   pdfversion=2.0,
+%   pdfstandard=ua-2,
+%   lang=en-US,
+% }
+
 \documentclass[12pt]{memoir}
 
 \usepackage{cdsc-memoir}
+% \usepackage{tagpdf}
+% \tagpdfsetup{activate-all}
 % there are two chapter styles: cdsc-article and cdsc-memo
 % memo assumes that you remove the "\\" and the email address from the
 % \author field below as well as that you will comment out the
@@ -28,7 +43,9 @@
 \usepackage[breaklinks]{hyperref}
 
 \hypersetup{colorlinks=true, linkcolor=Black, citecolor=Black, filecolor=Blue,
-    urlcolor=Blue, unicode=true}
+    urlcolor=Blue, unicode=true,
+    pdflang={en-US},
+    pdfdisplaydoctitle=true}
 
 % list of footnote symbols for \thanks{}
 \makeatletter