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/index.html

@@ -320,6 +320,7 @@
       <div class="p3-help">click polso = seleziona · gizmo: T sposta / R ruota · drag = muovi · orbit = wheel/drag fondo · pan = shift+drag</div>
     </div>
     <aside class="p3-sidebar">
+      <div class="p3-group" data-group="pose">
       <div class="p3-section">
         <h3>Modalità</h3>
         <div class="p3-row">
@@ -388,6 +389,9 @@
         </div>
       </div>
 
+      </div><!-- /p3-group pose -->
+
+      <div class="p3-group" data-group="cameras" hidden>
       <div class="p3-section">
         <h3>Camera Nuwa (polso DX)</h3>
         <div class="p3-row">
@@ -460,6 +464,34 @@
         <div class="marker-info" id="p3CloudStatus">—</div>
       </div>
 
+      </div><!-- /p3-group cameras -->
+
+      <div class="p3-group" data-group="misc" hidden>
+      <div class="p3-section">
+        <h3>Tag locator</h3>
+        <div class="p3-row">
+          <label><input type="checkbox" id="p3TagPlaceMode"> <b>Modalità tag click</b> (click sul modello = piazza crocetta)</label>
+        </div>
+        <div class="p3-row">
+          <label>Tag
+            <select id="p3TagSelect">
+              <option value="10:40:wrist_sx">wrist sx (id=10, 40mm)</option>
+              <option value="1:20:nuwa_dx">nuwa dx (id=1, 20mm)</option>
+            </select>
+          </label>
+        </div>
+        <div class="p3-row">
+          <label>x <input id="p3TagPosX" type="number" readonly style="width:70px"> mm</label>
+          <label>y <input id="p3TagPosY" type="number" readonly style="width:70px"> mm</label>
+          <label>z <input id="p3TagPosZ" type="number" readonly style="width:70px"> mm</label>
+        </div>
+        <div class="p3-row">
+          <button id="p3TagSaveBtn" disabled>Salva</button>
+          <button id="p3TagClearBtn" disabled>✕ rimuovi</button>
+        </div>
+        <div class="marker-info" id="p3TagStatus">attiva la modalità tag click sopra, poi clicca sul modello 3D</div>
+      </div>
+
       <div class="p3-section">
         <h3>Debug</h3>
         <div class="p3-row">
@@ -478,6 +510,17 @@
         </div>
       </div>
 
+      <div class="p3-section">
+        <h3>Tag camera frontale</h3>
+        <div class="p3-row">
+          <label><input type="checkbox" id="p3ShowFrontTags"> Mostra tag visibili (quad + dim + dist)</label>
+        </div>
+        <div class="p3-row">
+          <label>IDs <input id="p3FrontTagIds" type="text" value="0-49" style="width:90px"></label>
+        </div>
+        <div class="marker-info" id="p3FrontTagStatus">—</div>
+      </div>
+
       <div class="p3-section">
         <button id="p3UnlockBtn">Sblocca braccia</button>
       </div>
@@ -485,7 +528,13 @@
       <div class="p3-section" id="p3ErrorBox" style="display:none">
         <div class="p3-error" id="p3ErrorText"></div>
       </div>
+      </div><!-- /p3-group misc -->
     </aside>
+    <nav class="p3-tabrail" aria-label="Pose 3D groups">
+      <button type="button" class="p3-tab active" data-target="pose">POSE</button>
+      <button type="button" class="p3-tab" data-target="cameras">CAMERAS</button>
+      <button type="button" class="p3-tab" data-target="misc">MISC</button>
+    </nav>
   </div>
 </section>