Reduce media bandwidth: compress uploads, add long-lived cache headers, gzip API

- Resize/re-encode every uploaded image server-side (posts, avatars, stories,
  shop products/logo, chat messages) via a shared sharp-based optimizer —
  caps dimensions to what's actually displayed and re-compresses in place,
  cutting a typical raw camera photo by ~90% with no visible quality loss
- Cap uploaded video resolution/bitrate (re-encode only when above 1280px/
  ~2.5Mbps) alongside the existing faststart step; apply faststart+cap to
  story and chat videos too (previously stored completely raw)
- Add long-lived Cache-Control to all /storage static routes so clients stop
  re-downloading unchanged media on every request
- Add gzip/brotli compression for JSON API responses (feed/explore/chat)

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

package-lock.json

@@ -12,6 +12,7 @@
                 "axios": "^1.6.7",
                 "bcryptjs": "^2.4.3",
                 "body-parser": "^1.20.2",
+                "compression": "^1.8.2",
                 "connect-redis": "^10.0.0",
                 "cors": "^2.8.5",
                 "dotenv": "^16.4.5",
@@ -2569,6 +2570,74 @@
             "integrity": "sha512-GpVkmM8vF2vQUkj2LvZmD35JxeJOLCwJ9cUkugyk2nuhbv3+mJvpLYYt+0+USMxE+oj+ey/lJEnhZw75x/OMcQ==",
             "dev": true
         },
+        "node_modules/compressible": {
+            "version": "2.0.18",
+            "resolved": "https://mirror-npm.runflare.com/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": "1.8.2",
+            "resolved": "https://mirror-npm.runflare.com/compression/-/compression-1.8.2.tgz",
+            "integrity": "sha512-o8vI5RE5A6EVVOd9o41jKp41aJom+QTEO/Bx8MYNjexMo/Bv2WOjUfZr+aL0WnYSgymUy6zeguqLTsIhV0gMvQ==",
+            "license": "MIT",
+            "dependencies": {
+                "bytes": "3.1.2",
+                "compressible": "~2.0.18",
+                "debug": "2.6.9",
+                "destroy": "1.2.0",
+                "negotiator": "~0.6.4",
+                "on-headers": "~1.1.0",
+                "safe-buffer": "5.2.1",
+                "vary": "~1.1.2"
+            },
+            "engines": {
+                "node": ">= 0.8.0"
+            },
+            "funding": {
+                "type": "opencollective",
+                "url": "https://opencollective.com/express"
+            }
+        },
+        "node_modules/compression/node_modules/debug": {
+            "version": "2.6.9",
+            "resolved": "https://mirror-npm.runflare.com/debug/-/debug-2.6.9.tgz",
+            "integrity": "sha512-bC7ElrdJaJnPbAP+1EotYvqZsb3ecl5wi6Bfi6BJTUcNowp6cvspg0jXznRTKDjm/E7AdgFBVeAPVMNcKGsHMA==",
+            "license": "MIT",
+            "dependencies": {
+                "ms": "2.0.0"
+            }
+        },
+        "node_modules/compression/node_modules/ms": {
+            "version": "2.0.0",
+            "resolved": "https://mirror-npm.runflare.com/ms/-/ms-2.0.0.tgz",
+            "integrity": "sha512-Tpp60P6IUJDTuOq/5Z8cdskzJujfwqfOTkrwIwj7IRISpnkJnT6SyJ4PCPnGMoFjC9ddhal5KVIYtAt97ix05A==",
+            "license": "MIT"
+        },
+        "node_modules/compression/node_modules/negotiator": {
+            "version": "0.6.4",
+            "resolved": "https://mirror-npm.runflare.com/negotiator/-/negotiator-0.6.4.tgz",
+            "integrity": "sha512-myRT3DiWPHqho5PrJaIRyaMv2kgYf0mUVgBNOYMuCH5Ki1yEiQaf/ZJuQ62nvpc44wL5WDbTX7yGJi1Neevw8w==",
+            "license": "MIT",
+            "engines": {
+                "node": ">= 0.6"
+            }
+        },
+        "node_modules/compression/node_modules/on-headers": {
+            "version": "1.1.0",
+            "resolved": "https://mirror-npm.runflare.com/on-headers/-/on-headers-1.1.0.tgz",
+            "integrity": "sha512-737ZY3yNnXy37FHkQxPzt4UZ2UWPWiCZWLvFZ4fu5cueciegX0zGPnrlY6bwRg4FdQOe9YU8MkmJwGhoMybl8A==",
+            "license": "MIT",
+            "engines": {
+                "node": ">= 0.8"
+            }
+        },
         "node_modules/concat-map": {
             "version": "0.0.1",
             "resolved": "https://registry.npmjs.org/concat-map/-/concat-map-0.0.1.tgz",