Initial commit: 3D Viewer application

Features:
- Vue 3 frontend with Three.js/Online3DViewer
- Node.js API with PostgreSQL and Redis
- Python worker for model conversion
- Docker Compose for deployment
- ViewCube navigation with drag rotation and 90° snap
- Cross-section, exploded view, and render settings
- Parts tree with visibility controls

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

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

frontend/src/components/viewer/ViewCube.vue

@@ -0,0 +1,73 @@
+<script setup lang="ts">
+import { ref, onMounted, onUnmounted } from 'vue'
+import { useViewerStore } from '@/stores/viewer'
+import {
+  getViewCubeService,
+  resetViewCubeService,
+  type ViewDirection,
+} from '@/services/viewCubeService'
+
+const viewerStore = useViewerStore()
+const containerRef = ref<HTMLElement | null>(null)
+let renderLoopId: number | null = null
+
+onMounted(() => {
+  if (containerRef.value) {
+    const service = getViewCubeService()
+    service.initialize(
+      containerRef.value,
+      (direction: ViewDirection) => {
+        viewerStore.animateCameraToView(direction)
+      },
+      (deltaX: number, deltaY: number) => {
+        viewerStore.rotateCamera(deltaX, deltaY)
+      },
+      (direction: ViewDirection) => {
+        // When directly facing a face and clicking it, rotate 90° clockwise
+        viewerStore.rotateCameraAroundAxis(direction)
+      }
+    )
+
+    // Start render loop to keep ViewCube in sync with main camera
+    startRenderLoop()
+  }
+})
+
+function startRenderLoop(): void {
+  const sync = () => {
+    const service = getViewCubeService()
+    if (service.isInitialized() && viewerStore.camera) {
+      service.syncWithMainCamera(viewerStore.camera)
+    }
+    renderLoopId = requestAnimationFrame(sync)
+  }
+  renderLoopId = requestAnimationFrame(sync)
+}
+
+onUnmounted(() => {
+  if (renderLoopId !== null) {
+    cancelAnimationFrame(renderLoopId)
+  }
+  resetViewCubeService()
+})
+</script>
+
+<template>
+  <div class="viewcube-container" ref="containerRef"></div>
+</template>
+
+<style scoped>
+.viewcube-container {
+  position: absolute;
+  top: 16px;
+  right: 16px;
+  width: 100px;
+  height: 100px;
+  z-index: 20;
+  border-radius: 8px;
+  overflow: hidden;
+  background: rgba(0, 0, 0, 0.2);
+  backdrop-filter: blur(4px);
+  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
+}
+</style>