feat: Phase 3 complete — push alerts, feedback scoring, S3 fallback, SPA routing, mobile CSS

- ImpactScoreService: implement getFeedbackBonus() (ST_Distance query on UserFeedback within 20km/6h)
- ImpactScoreService: trigger PushNotificationService when score >= 70
- PushNotificationService: send VAPID WebPush to spot subscribers, clean expired subs
- PushController: GET vapid-public-key, POST/DELETE subscribe with rate limiting
- SentinelHubClient: add optional $collection param, add Sentinel-3 OLCI FAI evalscript (MCI)
- IngestionService: add $collection param + HighCloudCoverageException for fallback logic
- IngestionService: add ingestWithFallback() — tries S2, falls back to S3 on high cloud
- IngestSentinelCommand: --source=auto (default) triggers ingestWithFallback
- FeedbackController: rate limiting via apiFeedbackLimiter
- Migration: push_subscription table
- rate_limiter.yaml: api_read(120/min), api_feedback(10/min), api_push(5/min)
- sw.js: service worker handling push events + notificationclick
- usePushSubscription hook: subscribe/unsubscribe lifecycle with VAPID
- SpotPanel: PushButton component integrated
- SpotPanel.css + TimelineSlider.css: mobile responsive (bottom-sheet on small screens)
- Caddyfile: SPA served at / with try_files fallback, sw.js served from root scope
- vite.config.js: build outDir → backend/public (not /spa)
- deploy/post-receive.sh: full deploy script (composer, npm build, migrations, cache, docker up)
- docs/roadmap.md: all Phase 3 + transversal items marked done

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

frontend/src/hooks/usePushSubscription.js

@@ -0,0 +1,70 @@
+import { useState, useEffect } from 'react';
+import { api } from '../api/client';
+
+function urlBase64ToUint8Array(base64String) {
+  const padding = '='.repeat((4 - (base64String.length % 4)) % 4);
+  const base64  = (base64String + padding).replace(/-/g, '+').replace(/_/g, '/');
+  const raw     = window.atob(base64);
+  return Uint8Array.from([...raw].map((c) => c.charCodeAt(0)));
+}
+
+/**
+ * Hook managing the Web Push subscription lifecycle for a given coastalPointId.
+ * Returns { supported, subscribed, loading, error, toggle }
+ */
+export default function usePushSubscription(coastalPointId) {
+  const [supported,  setSupported]  = useState(false);
+  const [subscribed, setSubscribed] = useState(false);
+  const [loading,    setLoading]    = useState(false);
+  const [error,      setError]      = useState(null);
+
+  useEffect(() => {
+    setSupported('serviceWorker' in navigator && 'PushManager' in window);
+  }, []);
+
+  useEffect(() => {
+    if (!supported) return;
+
+    navigator.serviceWorker.ready.then((reg) =>
+      reg.pushManager.getSubscription()
+    ).then((sub) => {
+      setSubscribed(sub !== null);
+    }).catch(() => {});
+  }, [supported]);
+
+  const toggle = async () => {
+    if (!supported || loading) return;
+    setLoading(true);
+    setError(null);
+
+    try {
+      const reg = await navigator.serviceWorker.ready;
+      const existingSub = await reg.pushManager.getSubscription();
+
+      if (existingSub) {
+        await api.push.unsubscribe(existingSub.endpoint).catch(() => {});
+        await existingSub.unsubscribe();
+        setSubscribed(false);
+      } else {
+        const { publicKey } = await api.push.vapidKey();
+        const sub = await reg.pushManager.subscribe({
+          userVisibleOnly:      true,
+          applicationServerKey: urlBase64ToUint8Array(publicKey),
+        });
+        const json = sub.toJSON();
+        await api.push.subscribe({
+          endpoint:      json.endpoint,
+          keys:          json.keys,
+          coastalPointId,
+        });
+        setSubscribed(true);
+      }
+    } catch (e) {
+      setError(e.message ?? 'Erreur abonnement push');
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  return { supported, subscribed, loading, error, toggle };
+}