task(CAD-14): phase 4b - dynamic plugin tools section in left sidebar (all registry tools reachable, single tool location)

frontend/src/components/LeftSidebar.tsx

@@ -1,6 +1,7 @@
-import React, { useState, useCallback } from 'react';
+import React, { useState, useCallback, useMemo } from 'react';
 import type { LeftSidebarProps } from '../types/ui.types';
 import { SEATING_TEMPLATES } from '../services/seatingService';
+import { pluginRegistry } from '../plugins';
 
 interface ToolDef {
   tool: string;
@@ -138,6 +139,35 @@ const LeftSidebar: React.FC<LeftSidebarProps> = ({ activeTool, onToolChange, sel
         </div>
       ))}
 
+      {/* CAD-14 Phase 4b: Dynamische Sektion fuer Registry-Werkzeuge ohne
+          statischen Button (truss, boxcorner, circle-truss, measure, ...).
+          Ein Ort fuer ALLE Werkzeuge — keine Doppelung mehr. */}
+      {(() => {
+        const staticIds = new Set(sections.flatMap((s) => s.tools.map((t) => t.tool)));
+        const v2Tools = pluginRegistry.getToolsV2().filter((t) => !staticIds.has(t.manifest.id));
+        if (v2Tools.length === 0) return null;
+        return (
+          <div className="tool-section" key="v2-extra">
+            {renderSectionLabel('Werkzeuge (Plugins)', 'v2-extra')}
+            <div className="tool-grid" style={collapsedSections['v2-extra'] ? { display: 'none' } : undefined}>
+              {v2Tools.map((tool) => (
+                <button
+                  key={tool.manifest.id}
+                  className={`tool-btn${activeTool === tool.manifest.id ? ' active' : ''}`}
+                  data-v2tool={tool.manifest.id}
+                  data-tool={tool.manifest.id}
+                  title={tool.manifest.description ?? tool.manifest.label}
+                  onClick={() => onToolChange(tool.manifest.id)}
+                >
+                  <span className="tool-btn-label" style={{ fontSize: 14 }}>{tool.manifest.icon}</span>
+                  <span className="tool-btn-label">{tool.manifest.label}</span>
+                </button>
+              ))}
+            </div>
+          </div>
+        );
+      })()}
+
       {(onGroup || onUngroup) && (
         <div className="tool-section" key="grouping">
           {renderSectionLabel("Gruppierung", "grouping")}