rebuild dev and build system with single marp server

- simplify development: single marp server on port 3000 instead of 3 processes
- rename klausur to klausurfolien for better naming
- update extract script to use 00-intro.md as template when no 01-*.md exists
- update makefile and package.json for new workflow
- add comprehensive AGENTS.md guidelines

scripts/generate-index.sh

@@ -246,19 +246,19 @@ for html in $(ls "$BUILD_DIR"/[0-9][0-9]-*.html 2>/dev/null | sort); do
 LINK
 done
 
-# Add klausur entry if it exists
-if [[ -f "$BUILD_DIR/klausur.html" ]]; then
+# Add klausurfolien entry if it exists
+if [[ -f "$BUILD_DIR/klausurfolien.html" ]]; then
   pdf_link=""
-  if [[ -f "$BUILD_DIR/klausur.pdf" ]]; then
-    pdf_link="<a href=\"klausur.pdf\" class=\"btn btn-pdf\">PDF</a>"
+  if [[ -f "$BUILD_DIR/klausurfolien.pdf" ]]; then
+    pdf_link="<a href=\"klausurfolien.pdf\" class=\"btn btn-pdf\">PDF</a>"
   fi
   cat >> "$BUILD_DIR/index.html" << KLAUSUR
     <div class="kapitel-card" style="border-left: 3px solid $ACCENT_COLOR;">
-      <a href="klausur.html" class="kapitel-link">
+      <a href="klausurfolien.html" class="kapitel-link">
         <div class="kapitel-label">Prüfung</div>
         <div class="kapitel-title">Klausurrelevante Folien</div>
       </a>
-      <a href="klausur.html" class="btn btn-slides">Folien</a>
+      <a href="klausurfolien.html" class="btn btn-slides">Folien</a>
       $pdf_link
     </div>
 KLAUSUR