feat: Entity 선택기능, Property Inspector 패널, Layer 관리 패널, 드래그/접기/크기조절 UI 구현

src/viewer2d/Viewer2D.d.ts

@@ -11,6 +11,9 @@ export class Viewer2D {
   /** Resync renderer/camera to the container size (call after un-hiding). */
   resize(): void;
   onSelect(cb: (entity: unknown) => void): void;
+  getSelectedEntity(): unknown;
+  zoomToSelection(): void;
+  setAccent(hex: string): void;
   setTheme(dark: boolean): void;
   setGrid(visible: boolean): void;
   getLayerInfo(): { name: string; colorHex: string; count: number; visible: boolean }[];

src/viewer2d/Viewer2D.js

@@ -3535,6 +3535,52 @@ export class Viewer2D {
     if (this._selMeta) { const m = this._selMeta; this._selMeta = null; this._highlight(m); }
   }
 
+  /** Get currently selected CAD entity (or null). */
+  getSelectedEntity() {
+    return this._selMeta ? this._selMeta.entity : null;
+  }
+
+  /** Zoom extents to the currently selected CAD entity. */
+  zoomToSelection() {
+    if (!this._selMeta) return;
+    const idx = this._entityMeta.indexOf(this._selMeta);
+    if (idx < 0) return;
+    const box = new THREE.Box3();
+    const S = this._pickSegs, SM = this._pickSegMeta;
+    if (S && SM) {
+      for (let i = 0, j = 0; i < S.length; i += 4, j++) {
+        if (SM[j] === idx) {
+          box.expandByPoint(new THREE.Vector3(S[i], S[i + 1], 0));
+          box.expandByPoint(new THREE.Vector3(S[i + 2], S[i + 3], 0));
+        }
+      }
+    }
+    if (this._pickFills) {
+      for (const f of this._pickFills) {
+        if (f.metaIdx === idx) {
+          for (const loop of f.loops || []) {
+            for (const p of loop) {
+              box.expandByPoint(new THREE.Vector3(p.x, p.y, 0));
+            }
+          }
+        }
+      }
+    }
+    if (box.isEmpty() && this._selMeta.entity) {
+      const e = this._selMeta.entity;
+      const d = e.data || e;
+      const pt = d.start || d.center || d.pos || d.insertionPoint || d.insertionPt;
+      if (pt) {
+        const pad = 10;
+        box.expandByPoint(new THREE.Vector3(pt.x - pad, pt.y - pad, 0));
+        box.expandByPoint(new THREE.Vector3(pt.x + pad, pt.y + pad, 0));
+      }
+    }
+    if (!box.isEmpty()) {
+      this._fit(box);
+    }
+  }
+
   _distToBounds(wx, wy, b) {
     if (b.type === 'point')  return Math.hypot(wx - b.cx, wy - b.cy);
     if (b.type === 'circle') return Math.abs(Math.hypot(wx - b.cx, wy - b.cy) - b.r);