feat: galeria muestra foto impresa + estimacion por placa en detalle

- Galeria: cards muestran imagen de referencia si existe, fallback a thumbnail 3D
- Detalle: nueva seccion 'Placas de impresion' con estimacion individual por parte
- Endpoint /estimate ahora acepta file_id para calcular por archivo
- Visualizacion de placa 220x220mm con proporcion de pieza y totales acumulados

static/detail.html

@@ -171,6 +171,17 @@
             <div id="validation-result" class="hidden p-4 rounded-xl bg-slate-900/50 border border-white/5 text-sm space-y-1"></div>
             <div id="estimation-result" class="hidden p-4 rounded-xl bg-slate-900/50 border border-white/5 text-sm space-y-1"></div>
 
+            <!-- Plates Estimation -->
+            <div class="glass rounded-2xl p-5 border border-white/5">
+              <div class="flex items-center justify-between mb-3">
+                <label class="text-xs font-medium text-slate-500 uppercase tracking-wider block">Placas de impresion</label>
+                <button onclick="runPlateEstimation()" class="px-3 py-1.5 rounded-lg bg-cyan-500/20 text-cyan-400 hover:bg-cyan-500/30 text-xs font-medium transition-colors">
+                  Calcular placas
+                </button>
+              </div>
+              <div id="plates-result" class="space-y-3"></div>
+            </div>
+
             <div class="pt-4 flex gap-3">
               <a id="btn-download" href="#" class="flex-1 px-5 py-3 rounded-xl bg-gradient-to-r from-cyan-500 to-blue-600 hover:from-cyan-400 hover:to-blue-500 text-white font-bold text-sm shadow-lg shadow-cyan-500/20 transition-all hover:scale-[1.02] text-center flex items-center justify-center gap-2">
                 <svg class="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 16v1a3 3 0 003 3h10a3 3 0 003-3v-1m-4-8l-4-4m0 0L8 8m4-4v12"></path></svg>