P4-C: PWA installable, service worker push & campagne de fiabilité dialogues

- PWA: public/manifest.webmanifest + icon.svg + meta index.html (theme-color, apple-touch-icon)
- public/sw.js: service worker push-only (push → showNotification tag=sessionId ;
  notificationclick → focus/ouvre /sessions/<id>) — pas de précache (hors périmètre)
- lib/push.ts + stores/push.ts: enable/disable, abonnement VAPID, enregistrement SW au boot
- DashboardView: toggle « Notifications » (gardé par pushSupported) + i18n en/fr
- campagne de fiabilité (verdict S3): classification de tous les types de dialogue sur captures
  réelles (trust/permission×2/question) + refus Esc (deny-esc2) + plan (synthétique)
- acceptance-p4.mjs: VAPID/auth/Origin, subscribe idempotent/unsubscribe, answer (rejets)

Choix: SW écrit à la main plutôt que vite-plugin-pwa (qui tirait ~295 paquets Workbox +
2 vulns esbuild high pour un SW push-only). Zéro dépendance front nouvelle. 175 tests verts,
acceptance p1..p4 ALL GREEN.

package-lock.json

@@ -880,6 +880,19 @@
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+      "license": "MIT",
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+      "peer": true,
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+      "license": "MIT",
+      "optional": true,
+      "peer": true,
+      "bin": {
+        "acorn": "bin/acorn"
+      },
+      "engines": {
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+      "license": "MIT",
+      "optional": true,
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+      "resolved": "https://registry.npmjs.org/commander/-/commander-2.20.3.tgz",
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+      "license": "MIT",
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@@ -4241,6 +4287,31 @@
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+      "resolved": "https://registry.npmjs.org/source-map-support/-/source-map-support-0.5.21.tgz",
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+      "dev": true,
+      "license": "MIT",
+      "optional": true,
+      "peer": true,
+      "dependencies": {
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+      }
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+      "dev": true,
+      "license": "BSD-3-Clause",
+      "optional": true,
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@@ -4380,6 +4451,27 @@
         "node": ">=6"
       }
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+      "dev": true,
+      "license": "BSD-2-Clause",
+      "optional": true,
+      "peer": true,
+      "dependencies": {
+        "@jridgewell/source-map": "^0.3.3",
+        "acorn": "^8.15.0",
+        "commander": "^2.20.0",
+        "source-map-support": "~0.5.20"
+      },
+      "bin": {
+        "terser": "bin/terser"
+      },
+      "engines": {
+        "node": ">=10"
+      }
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     "node_modules/thread-stream": {
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