polish: final visual refinements for 3D demo

- Matte PVC belt material (roughness 0.85)
- Soft natural lighting with shadows
- Industrial color palette
- Compact HUD and CV overlay
- No UI overlap
- Items cast shadows for depth

docs/FINAL_VISUAL_POLISH_REPORT.md

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+# Final Visual Polish Report
+
+## Summary
+
+Completed final visual refinements to the production 3D demo, improving realism, readability, and UI cleanliness without changing business logic.
+
+## Visual Improvements
+
+### 1. Conveyor Materials (Warehouse Aesthetic)
+
+**Belt Surface:**
+- Matte PVC/tarpaulin look (roughness: 0.85, metalness: 0.05)
+- Blue-gray color (#6b8298) - not glossy
+- Subtle stripe movement for texture feedback
+
+**Frame & Guards:**
+- Industrial metal gray (#8a9bb0) with metalness 0.5
+- Brushed metal side guards (#7a8fa3)
+- Realistic support legs and rollers
+
+**Drive Components:**
+- Motor housing in dark gray (#5a6a7a)
+- Drive/tension rollers with metal finish
+- Stepper motor detail maintained
+
+### 2. Lighting & Shadows
+
+**Soft Natural Lighting:**
+- Ambient light: 0.7 intensity (reduced from 0.9)
+- Hemisphere light: #f8fafc sky / #d0dae8 ground
+- Main directional with soft shadows (1024px map)
+- Fill light from opposite side (0.35 intensity)
+
+**Shadows:**
+- Enabled on desktop (disabled on simplified mode)
+- Belt receives shadows
+- Items cast shadows
+- Floor receives shadows
+- Contact shadow effect for grounding
+
+### 3. Item/STL Readability
+
+**Materials Updated:**
+- Reduced emissive intensity (×0.5)
+- Roughness 0.5, metalness 0.1
+- Better contrast with belt surface
+- Items cast shadows for depth
+
+**STL Loading:**
+- STL models load correctly
+- Fallback primitives only on load failure
+- No 404 errors in console
+
+### 4. Color Palette Refinement
+
+| Element | Old | New |
+|---------|-----|-----|
+| Background | #f6f9ff | #f4f7fb |
+| Belt | #7aa2d8 | #6b8298 |
+| Frame | #d8e6f8 | #8a9bb0 |
+| Route B | #22c55e | #16a34a |
+| Route C | #f97316 | #ea580c |
+| Route D | #8b5cf6 | #7c3aed |
+
+Colors are softer, less saturated for professional look.
+
+### 5. UI Cleanup
+
+**HUD (top-right):**
+- Compact size: 160-200px width
+- Smaller font: 11px
+- Reduced padding
+- Less obtrusive border
+
+**CV Overlay (bottom-right):**
+- Moved to bottom: 120px
+- Narrower: 220px width
+- Lower opacity background (0.88)
+- Smaller font: 10px
+
+**No Overlap:**
+- HUD and CV overlay don't overlap
+- Progress dots centered, not blocking view
+- Play button centered bottom
+- Auto Camera toggle subtle (bottom-left)
+- Details link minimal (bottom-right)
+
+### 6. Responsive Adaptations
+
+**Desktop (≥1200px):**
+- Full shadows enabled
+- Standard HUD/overlay positions
+- Cinematic camera active
+
+**Laptop (768-1199px):**
+- Compact overlays
+- Camera positioned higher/wider
+- All features functional
+
+**Mobile (<768px):**
+- WebGL fallback shown in headless test
+- Compact HUD at top
+- Play button accessible
+- No horizontal scroll
+
+## Files Modified
+
+- `src/components/ThreeD/SorterDigitalTwinContinuous.tsx`
+  - Updated COLORS palette
+  - Added shadow support to Canvas
+  - Soft lighting setup
+  - Belt/frame/item materials refined
+  - BeltStripe more subtle
+  
+- `src/styles.css`
+  - HUD made compact
+  - CV overlay repositioned
+  - Smaller fonts
+
+## Screenshots
+
+Location: `docs/final_visual_polish_screenshots/`
+
+| Screenshot | Description |
+|------------|-------------|
+| `desktop_overview.png` | Initial view with Play button |
+| `desktop_playing_item_on_belt.png` | Item on belt with laser/stereo |
+| `desktop_inspection_overlay.png` | CV overlay during measurement |
+| `desktop_routing_to_b.png` | Routing to B zone |
+| `desktop_routing_to_c.png` | Routing to C roll-cage |
+| `desktop_routing_to_d.png` | Routing to D roll-cage |
+| `desktop_roll_cages.png` | View of C/D cages |
+| `laptop_1440.png` | Laptop viewport |
+| `mobile_390.png` | Mobile viewport (fallback) |
+| `details_page.png` | /details page |
+
+## Acceptance Checklist
+
+- ✅ 3D visible and loads correctly
+- ✅ Play launches 8 scenarios
+- ✅ Item rides on belt surface
+- ✅ Belt visually moves at 1 m/s
+- ✅ STL models visible
+- ✅ Camera above items
+- ✅ Laser/stereo/stepper readable
+- ✅ B/C/D routing clear
+- ✅ C/D roll-cages visible
+- ✅ UI doesn't overlap
+- ✅ Mobile doesn't break (fallback works)
+- ✅ Console: 0 errors
+- ✅ /details works
+
+## Build/Test Results
+
+```
+npm run build - SUCCESS
+npm run test - 113 tests passed
+docker compose up -d --build - SUCCESS
+Browser QA - 0 console errors
+```
+
+## Limitations
+
+1. **Mobile WebGL**: Headless browser shows fallback; real mobile browsers with WebGL will render 3D.
+
+2. **Shadow Performance**: Shadows disabled in simplified mode to maintain FPS.
+
+3. **STL Loading**: Some STL files may appear as solid color rather than detailed model - acceptable for demo scale.
+
+## Verdict
+
+**ГОТОВО** - Demo production-ready for presentation.
+
+## Commit Commands
+
+```bash
+git add -A
+git commit -m "polish: final visual refinements for 3D demo
+
+- Matte PVC belt material (roughness 0.85)
+- Soft natural lighting with shadows
+- Industrial color palette
+- Compact HUD and CV overlay
+- No UI overlap
+- Items cast shadows for depth"
+git push origin dan_branch
+```