Dash web: crosshair, zoom/pan X, scale log/lin, continuum extraction, background resume

- Tooltip entier (intersect:false) + ligne verticale crosshair sur tous les graphes
- Zoom molette/pinch sur l'axe X, pan souris, limites clamped 30-3000 keV
- Toggle échelle log/linéaire onglet Background
- Extraction continuum détecteur (isotope peaks subtracted + Gaussian smoothing)
- Reprise snapshot précédent au démarrage capture_background.py
- Suppression refs "Théorique" et "Bruit capteur" de l'interface
- Plugin chartjs-plugin-zoom + hammerjs via CDN
- Fix Chart constructor spread operator

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/static/css/style.css

@@ -78,6 +78,8 @@ main { padding: 16px; }
     border-radius: 8px;
     padding: 12px;
     margin-bottom: 12px;
+    height: 450px;
+    position: relative;
 }
 
 .controls {
@@ -108,6 +110,63 @@ main { padding: 16px; }
 
 .controls button:hover { background: var(--accent-bright); color: #000; }
 
+.btn-small {
+    background: var(--accent);
+    color: var(--text);
+    border: 1px solid #444;
+    padding: 4px 10px;
+    border-radius: 4px;
+    cursor: pointer;
+    font-size: 0.8em;
+    margin-left: auto;
+}
+.btn-small:hover { background: var(--accent-bright); color: #000; }
+
+.chart-container.fullscreen {
+    position: fixed;
+    top: 0; left: 0; right: 0; bottom: 0;
+    z-index: 1000;
+    background: var(--bg);
+    padding: 20px;
+    margin: 0;
+    border-radius: 0;
+    display: flex;
+    flex-direction: column;
+}
+.chart-container.fullscreen canvas {
+    flex: 1;
+}
+.exit-fullscreen-btn {
+    display: none;
+    position: absolute;
+    top: 10px;
+    right: 14px;
+    z-index: 1001;
+    background: rgba(255,255,255,0.15);
+    color: #fff;
+    border: none;
+    border-radius: 50%;
+    width: 36px;
+    height: 36px;
+    font-size: 1.2em;
+    cursor: pointer;
+    line-height: 1;
+}
+.chart-container.fullscreen .exit-fullscreen-btn {
+    display: flex;
+    align-items: center;
+    justify-content: center;
+}
+.exit-fullscreen-btn:hover {
+    background: rgba(255,255,255,0.3);
+}
+
+.chart-header {
+    display: flex;
+    justify-content: flex-end;
+    margin-bottom: 4px;
+}
+
 #isotopes-table, #peaks-table {
     background: var(--bg-card);
     border-radius: 8px;