Refactor symbols app: cleanup and fix issues

- Removed duplicate files (index2/3/4.html, symbols.js duplicates)
- Kept index4.html as the main index.html (modular version)
- Removed old text-generator.js (replaced by modular version)
- Fixed ID mismatch in ui-bindings.js to match HTML
- Added square and circle shape support in svg-generator.js
- Added legend preview with copy functionality
- Removed 580 lines of obsolete text-generator v4 code from app.js
- Added addTextToLegend and addStandaloneArrowToLegend to export.js

Still TODO: Split large files to comply with 300 line limit
- app.js: 1219 lines
- styles.css: 1319 lines
- symbols.js: 870 lines

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

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

symbols/js/text-generator/export.js

@@ -319,3 +319,44 @@ window.downloadStandaloneArrowDXF = function() {
         window.TextExport.downloadDxf(svg, 'pfeil.dxf');
     }
 };
+
+// Zur Legende hinzufuegen
+window.addTextToLegend = function() {
+    var state = window.TextGenState.current;
+    var svg = window.SvgGenerator.generate(state);
+    var name = state.text || 'Text-Symbol';
+
+    if (typeof legendItems !== 'undefined' && typeof updateLegendCount === 'function') {
+        legendItems.push({
+            id: 'text_' + Date.now(),
+            name: name.split('\n')[0].substring(0, 30),
+            svg: svg,
+            description: ''
+        });
+        updateLegendCount();
+        saveLegendToStorage();
+        if (typeof showNotification === 'function') {
+            showNotification('Zur Legende hinzugefuegt!');
+        }
+    }
+};
+
+window.addStandaloneArrowToLegend = function() {
+    var state = window.TextGenState.current;
+    var svg = window.SvgGenerator.generateArrowOnly(state);
+    if (!svg) return;
+
+    if (typeof legendItems !== 'undefined' && typeof updateLegendCount === 'function') {
+        legendItems.push({
+            id: 'arrow_' + Date.now(),
+            name: 'Pfeil ' + state.arrow,
+            svg: svg,
+            description: ''
+        });
+        updateLegendCount();
+        saveLegendToStorage();
+        if (typeof showNotification === 'function') {
+            showNotification('Pfeil zur Legende hinzugefuegt!');
+        }
+    }
+};