Supprime nginx : Express sert le frontend, ports peu utilisés

- Un seul conteneur applicatif : Express sert l'API, le frontend React
  compilé (fallback SPA, cache immutable sur /assets) et les images
  /uploads (nosniff + CSP default-src 'none')
- En-têtes de sécurité (CSP stricte, X-Frame-Options DENY, etc.) portés
  de nginx vers helmet, compression gzip ajoutée
- Application exposée sur le port 8321 (APP_PORT), PostgreSQL sur
  127.0.0.1:56432 (DB_PORT, loopback uniquement pour l'admin locale)
- TRUST_PROXY pilote la confiance aux en-têtes X-Forwarded-* (désactivé
  par défaut hors reverse-proxy)
- Dockerfile multi-étages unique à la racine (build React → deps → image
  finale non-root, fs en lecture seule)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Fkg15RCxNgUys4ru73He2o

server/package-lock.json

@@ -9,6 +9,7 @@
       "version": "1.0.0",
       "dependencies": {
         "bcryptjs": "^2.4.3",
+        "compression": "^1.7.4",
         "cookie-parser": "^1.4.6",
         "express": "^4.19.2",
         "express-rate-limit": "^7.4.0",
@@ -135,6 +136,45 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
+    "node_modules/compressible": {
+      "version": "2.0.18",
+      "resolved": "https://registry.npmjs.org/compressible/-/compressible-2.0.18.tgz",
+      "integrity": "sha512-AF3r7P5dWxL8MxyITRMlORQNaOA2IkAFaTr4k7BUumjPtRpGDTZpl0Pb1XCO6JeDCBdp126Cgs9sMxqSjgYyRg==",
+      "license": "MIT",
+      "dependencies": {
+        "mime-db": ">= 1.43.0 < 2"
+      },
+      "engines": {
+        "node": ">= 0.6"
+      }
+    },
+    "node_modules/compression": {
+      "version": "1.8.1",
+      "resolved": "https://registry.npmjs.org/compression/-/compression-1.8.1.tgz",
+      "integrity": "sha512-9mAqGPHLakhCLeNyxPkK4xVo746zQ/czLH1Ky+vkitMnWfWZps8r0qXuwhwizagCRttsL4lfG4pIOvaWLpAP0w==",
+      "license": "MIT",
+      "dependencies": {
+        "bytes": "3.1.2",
+        "compressible": "~2.0.18",
+        "debug": "2.6.9",
+        "negotiator": "~0.6.4",
+        "on-headers": "~1.1.0",
+        "safe-buffer": "5.2.1",
+        "vary": "~1.1.2"
+      },
+      "engines": {
+        "node": ">= 0.8.0"
+      }
+    },
+    "node_modules/compression/node_modules/negotiator": {
+      "version": "0.6.4",
+      "resolved": "https://registry.npmjs.org/negotiator/-/negotiator-0.6.4.tgz",
+      "integrity": "sha512-myRT3DiWPHqho5PrJaIRyaMv2kgYf0mUVgBNOYMuCH5Ki1yEiQaf/ZJuQ62nvpc44wL5WDbTX7yGJi1Neevw8w==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 0.6"
+      }
+    },
     "node_modules/concat-stream": {
       "version": "1.6.2",
       "resolved": "https://registry.npmjs.org/concat-stream/-/concat-stream-1.6.2.tgz",
@@ -805,6 +845,15 @@
         "node": ">= 0.8"
       }
     },
+    "node_modules/on-headers": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/on-headers/-/on-headers-1.1.0.tgz",
+      "integrity": "sha512-737ZY3yNnXy37FHkQxPzt4UZ2UWPWiCZWLvFZ4fu5cueciegX0zGPnrlY6bwRg4FdQOe9YU8MkmJwGhoMybl8A==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 0.8"
+      }
+    },
     "node_modules/parseurl": {
       "version": "1.3.3",
       "resolved": "https://registry.npmjs.org/parseurl/-/parseurl-1.3.3.tgz",