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/app/routers/spectrum.py

@@ -1,6 +1,7 @@
 import json
 from fastapi import APIRouter, HTTPException
-from app.config import STATE_PATH, BACKGROUND_PATH, energy_axis, NUM_CHANNELS
+from app.config import (STATE_PATH, BACKGROUND_PATH, energy_axis, NUM_CHANNELS,
+                        clip_to_range, correct_csi_nonlinear)
 import numpy as np
 
 router = APIRouter()
@@ -8,7 +9,7 @@ router = APIRouter()
 
 @router.get("/current")
 async def get_current_spectrum():
-    """Current accumulated spectrum with energy axis."""
+    """Current accumulated spectrum with energy axis (CsI-corrected)."""
     if not STATE_PATH.exists():
         raise HTTPException(status_code=503, detail="Monitor not started yet")
 
@@ -18,6 +19,9 @@ async def get_current_spectrum():
     except (json.JSONDecodeError, OSError):
         raise HTTPException(status_code=503, detail="Monitor state file corrupt")
 
+    raw_counts = state.get("counts", [0] * 1024)[:NUM_CHANNELS]
+    # Apply CsI correction so peaks appear at theoretical energy positions
+    corrected_counts = correct_csi_nonlinear(np.array(raw_counts, dtype=np.float64))
     return {
         "timestamp": state.get("timestamp", ""),
         "connected": state.get("connected", False),
@@ -27,15 +31,15 @@ async def get_current_spectrum():
         "total_counts": state.get("total_counts", 0),
         "background_subtracted": state.get("background_subtracted", False),
         "isotopes_detected": state.get("isotopes_detected", []),
-        "channels": list(range(NUM_CHANNELS)),
+        "channels": clip_to_range(list(range(NUM_CHANNELS))),
         "energy_kev": energy_axis(),
-        "counts": state.get("counts", [0] * 1024)[:NUM_CHANNELS],
+        "counts": clip_to_range([round(float(c), 1) for c in corrected_counts]),
     }
 
 
 @router.get("/difference")
 async def get_difference_spectrum():
-    """Background-subtracted spectrum (net signal)."""
+    """Background-subtracted spectrum (net signal, CsI-corrected)."""
     if not STATE_PATH.exists():
         raise HTTPException(status_code=503, detail="Monitor not started yet")
 
@@ -59,18 +63,21 @@ async def get_difference_spectrum():
         bg_live_time = float(bg_data["duration"])
         bg_rate = bg_counts / bg_live_time
         net_rate = np.clip(rate - bg_rate, 0, None)
-        net_counts = net_rate * live_time
+        # Apply CsI correction to net spectrum
+        corrected_net = correct_csi_nonlinear(net_rate)
+        net_counts = corrected_net * live_time
         bg_available = True
     else:
         net_counts = counts
         bg_available = False
 
+    net_counts_list = [round(float(c), 1) for c in net_counts]
     return {
         "timestamp": state.get("timestamp", ""),
         "cumulated_live_time_s": live_time,
         "background_subtracted": bg_available,
-        "channels": list(range(NUM_CHANNELS)),
+        "channels": clip_to_range(list(range(NUM_CHANNELS))),
         "energy_kev": energy_axis(),
-        "counts": [round(float(c), 1) for c in net_counts],
-        "raw_counts": state.get("counts", [])[:NUM_CHANNELS],
+        "counts": clip_to_range(net_counts_list),
+        "raw_counts": clip_to_range(state.get("counts", [])[:NUM_CHANNELS]),
     }