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/components/SpotPanel/SpotPanel.jsx

@@ -1,5 +1,6 @@
 import { useEffect, useState } from 'react';
 import { api } from '../../api/client';
+import usePushSubscription from '../../hooks/usePushSubscription';
 import './SpotPanel.css';
 
 const LEVEL_LABEL = { low: 'OK', medium: 'Risque', high: 'Impact' };
@@ -89,6 +90,7 @@ export default function SpotPanel({ spot, activeStep, onClose }) {
       </div>
 
       <FeedbackButton spot={spot} />
+      <PushButton spotId={spot.id} />
     </div>
   );
 }
@@ -123,3 +125,23 @@ function FeedbackButton({ spot }) {
     </div>
   );
 }
+
+function PushButton({ spotId }) {
+  const { supported, subscribed, loading, error, toggle } = usePushSubscription(spotId);
+
+  if (!supported) return null;
+
+  return (
+    <div className="spot-panel__push">
+      <button
+        className={`spot-panel__push-btn ${subscribed ? 'spot-panel__push-btn--active' : ''}`}
+        onClick={toggle}
+        disabled={loading}
+        aria-pressed={subscribed}
+      >
+        {loading ? '…' : subscribed ? '🔔 Alertes activées' : '🔕 Activer les alertes'}
+      </button>
+      {error && <p className="spot-panel__push-error">{error}</p>}
+    </div>
+  );
+}