perf: 系统性能优化 - 数据库索引、缓存、GZIP压缩和查询合并

- 添加3个复合索引提升查询性能 (user_date, user_category, destination)
- 添加GZIP压缩和静态资源缓存 (maxAge: 1h)
- 添加API响应no-cache头
- 添加stats端点2分钟内存缓存 (per-user key, LRU淘汰)
- 合并多次数据库查询为单次查询
- 添加滚动防抖改善移动端体验
- 修复res.once内存泄漏问题

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

package-lock.json

@@ -11,6 +11,7 @@
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+        "compression": "^1.8.1",
         "cors": "^2.8.6",
         "express": "^5.2.1",
         "jsonwebtoken": "^9.0.3"
@@ -190,6 +191,60 @@
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       "license": "ISC"
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+    "node_modules/compressible": {
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+      "resolved": "https://registry.npmjs.org/compressible/-/compressible-2.0.18.tgz",
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+      "license": "MIT",
+      "dependencies": {
+        "mime-db": ">= 1.43.0 < 2"
+      },
+      "engines": {
+        "node": ">= 0.6"
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+    "node_modules/compression": {
+      "version": "1.8.1",
+      "resolved": "https://registry.npmjs.org/compression/-/compression-1.8.1.tgz",
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+      "dependencies": {
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+        "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/debug": {
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+      "resolved": "https://registry.npmjs.org/debug/-/debug-2.6.9.tgz",
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+      "license": "MIT",
+      "dependencies": {
+        "ms": "2.0.0"
+      }
+    },
+    "node_modules/compression/node_modules/ms": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/ms/-/ms-2.0.0.tgz",
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+      "license": "MIT"
+    },
+    "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",
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+        "node": ">= 0.6"
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     "node_modules/content-disposition": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/content-disposition/-/content-disposition-1.0.1.tgz",
@@ -905,6 +960,15 @@
         "node": ">= 0.8"
       }
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+    "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/once": {
       "version": "1.4.0",
       "resolved": "https://registry.npmjs.org/once/-/once-1.4.0.tgz",