fix(drone): resolve drone feed fog and flicker issues

- Add preserveDrawingBuffer to enable automated test screenshots
- Neutralize scene fog during drone render pass to prevent misted aerial view
- Render drone feed every frame instead of alternating with ground view
- Update visor styling with scanline effect and improved borders
- Add debug getters for WebGL renderer and scene information

resources/views/city/viewer.blade.php

@@ -254,9 +254,13 @@
                         style="border:0; background:rgba(148,163,184,.18); color:#e2e8f0; border-radius:.35rem; cursor:pointer; padding:.1rem .45rem;">✕</button>
             </div>
             <div id="drone-video"
-                 style="height:200px; background:transparent;
-                        border-top:1px solid rgba(148,163,184,.35);
-                        border-bottom:1px solid rgba(148,163,184,.35);"></div>
+                 style="height:200px;
+                        background:repeating-linear-gradient(0deg,
+                            rgba(0,0,0,.14) 0px, rgba(0,0,0,.14) 2px,
+                            rgba(0,0,0,0) 2px, rgba(0,0,0,0) 4px);
+                        border:7px solid #050a14; border-radius:.4rem;
+                        box-shadow:inset 0 0 16px rgba(0,0,0,.75),
+                                   0 0 0 2px rgba(148,163,184,.45);"></div>
             <div id="drone-hints"
                  style="padding:.4rem .6rem; font-size:.7rem; color:#cbd5e1; background:rgba(2,8,20,.88);">
                 {{ __('city.drone_hint') }}