feat: unified drafts/ structure with PDF outputs for ACT and ECT

Both drafts now live in workspace/drafts/ as siblings:
  drafts/
  ├── act/                       (ACT -01, native to parent repo)
  │   ├── draft-nennemann-act-01.md     kramdown-rfc source
  │   ├── draft-nennemann-act-01.{xml,txt,html,pdf}
  │   ├── .refcache/             bibxml cache
  │   └── build.sh
  ├── ietf-wimse-ect/            (ECT -02, submodule, PDF added)
  │   └── ...
  └── README-pdf.md              PDF toolchain docs

ACT kramdown-rfc conversion:
- full YAML frontmatter (title, author, refs)
- section structure matches kramdown-rfc conventions
- {{REF}} citation syntax, auto-numbered sections
- references auto-built from normative/informative blocks
- removed manual TOC (kramdown-rfc generates)
- builds cleanly: 133K XML, 89K TXT, 208K HTML, 167K PDF

PDF toolchain:
- xml2rfc --pdf via weasyprint<60 + pydyf<0.10 injected into xml2rfc pipx venv
- both build.sh scripts now produce PDF as Step 4
- README-pdf.md documents the setup for new machines

Submodule: bump ietf-wimse-ect pointer for build.sh PDF step

workspace/drafts/act/build.sh

@@ -0,0 +1,69 @@
+#!/bin/bash
+set -e
+
+DIR="$(cd "$(dirname "$0")" && pwd)"
+SRC="$DIR/draft-nennemann-act-01.md"
+
+# Extract docname from YAML front matter
+DRAFT=$(grep '^docname:' "$SRC" | head -1 | awk '{print $2}')
+if [ -z "$DRAFT" ]; then
+  echo "Error: could not extract docname from $SRC"
+  exit 1
+fi
+
+# Tool paths
+KRAMDOWN="$(which kramdown-rfc2629 2>/dev/null)"
+XML2RFC="$(which xml2rfc 2>/dev/null)"
+
+if [ -z "$KRAMDOWN" ]; then
+  echo "Error: kramdown-rfc2629 not found. Install with: gem install kramdown-rfc2629"
+  exit 1
+fi
+if [ -z "$XML2RFC" ]; then
+  echo "Error: xml2rfc not found. Install with: pip install xml2rfc"
+  exit 1
+fi
+
+export PYTHONWARNINGS="ignore::UserWarning"
+
+echo "Building: $DRAFT"
+echo "Using kramdown-rfc2629: $KRAMDOWN"
+echo "Using xml2rfc:          $XML2RFC"
+echo ""
+
+# Step 1: Markdown -> XML
+echo "Converting markdown to XML..."
+"$KRAMDOWN" "$SRC" > "$DIR/$DRAFT.xml"
+
+# Step 2: XML -> TXT
+echo "Generating text output..."
+"$XML2RFC" "$DIR/$DRAFT.xml" --text --quiet 2>/dev/null
+
+# Step 3: XML -> HTML
+echo "Generating HTML output..."
+"$XML2RFC" "$DIR/$DRAFT.xml" --html --quiet 2>/dev/null
+
+# Step 4: XML -> PDF (requires weasyprint + pangocffi + pycairo injected into xml2rfc venv
+# and pydyf<0.10 pinned; see /home/c/projects/research.ietf/workspace/drafts/README-pdf.md)
+echo "Generating PDF output..."
+if "$XML2RFC" "$DIR/$DRAFT.xml" --pdf --quiet 2>/dev/null; then
+  PDF_OK=1
+else
+  echo "  xml2rfc --pdf failed; falling back to weasyprint on HTML"
+  if command -v weasyprint >/dev/null 2>&1; then
+    weasyprint "$DIR/$DRAFT.html" "$DIR/$DRAFT.pdf" >/dev/null 2>&1 && PDF_OK=1 || PDF_OK=0
+  else
+    PDF_OK=0
+  fi
+fi
+
+echo ""
+echo "Build complete:"
+echo "  $DRAFT.xml   (submit this to datatracker)"
+echo "  $DRAFT.txt"
+echo "  $DRAFT.html"
+if [ "${PDF_OK:-0}" = "1" ]; then
+  echo "  $DRAFT.pdf"
+else
+  echo "  (PDF generation skipped — missing deps)"
+fi