feat(pose_3d): tag locator save, front-tag overlay, sidebar tabs, cloud params persist

- Sidebar a 3 tab verticali (POSE / CAMERAS / MISC) per ridurre lo scroll
- Tag locator: POST /api/pose_3d/tag_offset/{save,} salva crocetta nel
  viewport con snapshot giunti, current.json + archive rotation
- Front-camera tag overlay (MISC):
  - GET /api/pose_3d/front_tags scansiona ArUco sul D435i e per ogni tag
    misura i 4 corner 3D via depth sensor (indipendente da solvePnP);
    outlier rejection ±20% dalla mediana per ignorare corner che catturano
    background sul bordo del marker
  - Rendering quad cyan + label compatta (id, edge_mm, distanza camera)
    agganciato al d435_link, segue la camera anche in modalita' hand-eye
  - Trigger via pollState() quando il flag e' on, niente timer separato
- Cloud cross-camera: memorizza step/max_depth/sizes/scale_xy/flip/handeye
  in pose_3d.cloud_params al click di Acquisisci, ripopola UI da config
  al primo poll (state.cloud_params_populated guard)
- D435i front cloud: applica nuwa_to_cv_frame (il servizio ritorna native,
  non OpenCV come si pensava)
- Cache-bust per pose_3d.js e pose_3d.css

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/pose_3d.css

@@ -1,11 +1,40 @@
 #tab-pose-3d .p3-layout {
   display: grid;
-  grid-template-columns: 1fr 360px;
+  grid-template-columns: 1fr 360px 92px;
   gap: 16px;
   height: calc(100vh - 140px);
   min-height: 600px;
 }
 
+#tab-pose-3d .p3-tabrail {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+  align-items: stretch;
+}
+#tab-pose-3d .p3-tab {
+  background: #1a1f26;
+  border: 1px solid #2a2f36;
+  color: #aab;
+  padding: 14px 8px;
+  border-radius: 6px;
+  font-size: 12px;
+  font-weight: bold;
+  letter-spacing: 1px;
+  cursor: pointer;
+  writing-mode: horizontal-tb;
+  text-align: center;
+}
+#tab-pose-3d .p3-tab:hover { background: #232a33; color: #e0e0e0; }
+#tab-pose-3d .p3-tab.active {
+  background: #1f3556;
+  border-color: #4da3ff;
+  color: #4da3ff;
+}
+
+#tab-pose-3d .p3-group { display: contents; }
+#tab-pose-3d .p3-group[hidden] { display: none; }
+
 #tab-pose-3d .p3-viewport {
   position: relative;
   background: #0d1014;