Add 22+ new building component symbols

- bauteile.js: Added Gipskartonwand (1-fach/2-fach), Fachwerkwand,
  Holzvertäfelung, Schacht, Gipskartondecke, Holzbalkendecke,
  Betondecke, Holzverkleidung Decke, Teppich, Doppelboden,
  Flachdach, Retentionsdach, Dachziegel, Dachlatte,
  PUR/EPS/XPS-Dämmung, Tor, Geländer
- elektro.js: New category with Steckdose, Doppelsteckdose,
  Lichtschalter, Verteilerdose, Sicherungskasten, Deckenlampe
- sanitaer.js: Added Duscharmatur, Gartenwasserhahn
- index.html: Added elektro.js script and Elektro filter pill

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

symbols/index.html

@@ -310,6 +310,7 @@
             <button class="filter-pill" data-filter="moebel">Moebel</button>
             <button class="filter-pill" data-filter="bad">Bad</button>
             <button class="filter-pill" data-filter="kueche">Kueche</button>
+            <button class="filter-pill" data-filter="elektro">Elektro</button>
             <button class="filter-pill" data-filter="pfeile">Pfeile</button>
             <button class="filter-pill" data-filter="kompass">Kompass</button>
             <span class="filter-divider">|</span>
@@ -442,6 +443,7 @@ document.addEventListener("keydown",function(e){if(e.key==="Escape"){closeImpres
     <script src="js/symbols/bauteile.js?v=2"></script>
     <script src="js/symbols/moebel.js?v=2"></script>
     <script src="js/symbols/sanitaer.js?v=2"></script>
+    <script src="js/symbols/elektro.js?v=2"></script>
     <script src="js/symbols/gutachten.js?v=2"></script>
     <script src="js/symbols/regenwasser.js?v=2"></script>
     <script src="js/symbols/vermessung.js?v=2"></script>