Dashboard web FastAPI + Chart.js

- 4 vues : spectre temps reel, historique detections, background, timeline CPS
- API REST : /api/status, /api/spectrum/current, /api/spectrum/difference,
  /api/background, /api/background/spectrum, /api/history, /api/cps/timeline
- Frontend vanilla JS + Chart.js (pas de Node.js, leger pour Pi 4)
- Moniteur modifie pour exporter son etat dans /data/monitor_state.json
  et le CPS dans /data/cps_log.jsonl chaque cycle
- Nouveau conteneur Docker 'web' sur port 8080
- Theme sombre, calibration energie (E = 0.33 + 2.97 * canal)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/app/routers/background.py

@@ -0,0 +1,66 @@
+import json
+from fastapi import APIRouter, HTTPException
+from app.config import BACKGROUND_SNAPSHOT_PATH, BACKGROUND_PATH, energy_axis, NUM_CHANNELS
+import numpy as np
+
+router = APIRouter()
+
+
+@router.get("")
+async def get_background_info():
+    """Background metadata: elapsed time, CPS, top peaks."""
+    if not BACKGROUND_SNAPSHOT_PATH.exists():
+        raise HTTPException(status_code=404, detail="Background capture not available yet")
+
+    try:
+        with open(BACKGROUND_SNAPSHOT_PATH) as f:
+            snapshot = json.load(f)
+    except (json.JSONDecodeError, OSError):
+        raise HTTPException(status_code=500, detail="Background snapshot file corrupt")
+
+    # Check if full background is available
+    full_available = BACKGROUND_PATH.exists()
+
+    return {
+        "elapsed_hours": snapshot.get("elapsed_hours", 0),
+        "live_time_s": snapshot.get("live_time_s", 0),
+        "total_counts": snapshot.get("total_counts", 0),
+        "cps": snapshot.get("cps", 0),
+        "top_peaks": snapshot.get("top_peaks", []),
+        "full_background_available": full_available,
+    }
+
+
+@router.get("/spectrum")
+async def get_background_spectrum():
+    """Full background spectrum with energy axis."""
+    if not BACKGROUND_SNAPSHOT_PATH.exists():
+        raise HTTPException(status_code=404, detail="Background capture not available yet")
+
+    try:
+        with open(BACKGROUND_SNAPSHOT_PATH) as f:
+            snapshot = json.load(f)
+    except (json.JSONDecodeError, OSError):
+        raise HTTPException(status_code=500, detail="Background snapshot file corrupt")
+
+    counts = snapshot.get("spectrum", [0] * NUM_CHANNELS)
+
+    # If full background file exists, use it for better data
+    if BACKGROUND_PATH.exists():
+        try:
+            bg_data = np.load(str(BACKGROUND_PATH), allow_pickle=True).item()
+            counts = [round(float(c), 1) for c in bg_data["counts"]]
+            live_time = float(bg_data["duration"])
+        except Exception:
+            live_time = snapshot.get("live_time_s", 0)
+    else:
+        live_time = snapshot.get("live_time_s", 0)
+
+    return {
+        "channels": list(range(NUM_CHANNELS)),
+        "energy_kev": energy_axis(),
+        "counts": counts,
+        "live_time_s": live_time,
+        "cps": snapshot.get("cps", 0),
+        "top_peaks": snapshot.get("top_peaks", []),
+    }