Fix: CsI(Tl) non-linear response correction + detector calibration overhaul

Root cause of Am-241 misidentification: the Radiacode 103's CsI(Tl) crystal
shifts low-energy peaks upward (59.5 keV → 71.6 keV for Am-241) due to
non-proportional scintillation response. The model was trained on theoretical
peak positions and couldn't match the shifted real peaks.

Changes:
- Add inverse CsI(Tl) non-linear correction to inference pipeline
  (radiacode_monitor.py, web/config.py, test_detection.py)
  E_apparent = E_true * (1 + 0.37 * exp(-E_true/100))
  Corrects channel mapping so peaks appear at theoretical energies
- Fix energy calibration: DetectorConfig now uses E = 0.33 + 2.97*ch
  with 1023 channels, matching the real detector (was energy_min=20,
  skip_first_channel=True, different channel width)
- Add K-escape peaks for CsI(Tl) iodine X-ray escape (E - 28.5 keV)
- Add asymmetric peak shapes for low-energy tails (< 200 keV)
- Add log1p normalization in dataset and inference (replaces max-norm)
- Add background-subtracted training mode (subtract_background flag)
- Add low-signal augmentation (0.01-5 Bq activities, 30-300s durations)
- Update docker-compose.yml: batch_size=32, duration=30-300s,
  CSI_NONLINEAR_ALPHA/BETA env vars for detect and web
- Web dashboard: apply CsI correction to displayed spectra
- Various UI fixes (Chart.js width, zoom/pan, isotope lines)

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

web/static/js/background.js

@@ -6,11 +6,11 @@ let bgContinuumData = null;
 document.getElementById('reset-zoom-bg')?.addEventListener('click', () => {
     if (bgChart) {
         bgChart.resetZoom();
-        // After resetZoom, force the scale to full energy range
+        delete bgChart._panRange;
         const firstPt = bgChart.data.datasets[0]?.data?.[0];
         const lastPt = bgChart.data.datasets[0]?.data?.[bgChart.data.datasets[0].data.length - 1];
         const fullMin = firstPt?.x ?? 0;
-        const fullMax = lastPt?.x ?? 3036;
+        const fullMax = lastPt?.x ?? 3000;
         bgChart.options.scales.x.min = fullMin;
         bgChart.options.scales.x.max = fullMax;
         bgChart.update();
@@ -170,12 +170,12 @@ function updateBackgroundChart(spec) {
         datasets: datasets,
     };
 
-    // Preserve pan range (user zoomed), but reset to full range when data refreshes
+    // Preserve pan range only if user has explicitly zoomed/panned
     const panRange = bgChart?._panRange;
-    const firstX = datasets[0].data[0]?.x;
-    const lastX = datasets[0].data[datasets[0].data.length - 1]?.x;
-    const xMin = panRange ? panRange[0] : (firstX ?? 0);
-    const xMax = panRange ? panRange[1] : (lastX ?? 3036);
+    const firstX = datasets[0].data[0]?.x ?? 0;
+    const lastX = datasets[0].data[datasets[0].data.length - 1]?.x ?? 3000;
+    const xMin = panRange ? panRange[0] : firstX;
+    const xMax = panRange ? panRange[1] : lastX;
     const options = {
         responsive: true,
         maintainAspectRatio: false,
@@ -214,8 +214,8 @@ function updateBackgroundChart(spec) {
             },
             y: {
                 type: showLog ? 'logarithmic' : 'linear',
+                min: showLog ? 0.5 : undefined,
                 title: { display: true, text: `Comptages (${showLog ? 'log' : 'lin'})`, color: '#888' },
-                ...(showLog ? { min: 0.9 } : {}),
                 ticks: { color: '#888' },
                 grid: { color: '#333' },
             }
@@ -229,7 +229,7 @@ function updateBackgroundChart(spec) {
     } else {
         bgChart = new Chart(ctx, { type: 'line', data: chartData, ...options });
         const firstX = datasets[0].data[0]?.x ?? 0;
-        const lastX = datasets[0].data[datasets[0].data.length - 1]?.x ?? 3036;
+        const lastX = datasets[0].data[datasets[0].data.length - 1]?.x ?? 3000;
         enablePan(bgChart, 'reset-zoom-bg', firstX, lastX);
     }
 }