Fix preview app startup on Node 22 (Express 5 route syntax) (#2536)

Express was bumped 4.21.2 -> 5.2.1, whose router uses path-to-regexp v8 which removed inline-regex route params. The route /pull/:pr(\d+) threw PathError at startup. Switch to /pull/:pr (handler already validates with /^\d+\$/ and returns 400).

Also update deploy runtime to NODE:22-lts and drop the stray 'node' and unused top-level 'path-to-regexp' dependencies.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 7793a516-0204-44e1-bed5-d8ad91b9400a

preview/package-lock.json

@@ -12,9 +12,7 @@
         "express": "^5.2.1",
         "follow-redirects": "^1.16.0",
         "http-proxy-middleware": "^3.0.7",
-        "node": "^20.19.5",
-        "node-fetch": "^2.6.1",
-        "path-to-regexp": "^0.1.13"
+        "node-fetch": "^2.6.1"
       }
     },
     "node_modules/@types/http-proxy": {
@@ -589,20 +587,6 @@
         "node": ">= 0.6"
       }
     },
-    "node_modules/node": {
-      "version": "20.19.5",
-      "hasInstallScript": true,
-      "license": "ISC",
-      "dependencies": {
-        "node-bin-setup": "^1.0.0"
-      },
-      "bin": {
-        "node": "bin/node.exe"
-      },
-      "engines": {
-        "npm": ">=5.0.0"
-      }
-    },
     "node_modules/node-fetch": {
       "version": "2.6.7",
       "license": "MIT",
@@ -621,10 +605,6 @@
         }
       }
     },
-    "node_modules/node/node_modules/node-bin-setup": {
-      "version": "1.1.4",
-      "license": "ISC"
-    },
     "node_modules/object-inspect": {
       "version": "1.13.4",
       "license": "MIT",
@@ -661,12 +641,6 @@
         "node": ">= 0.8"
       }
     },
-    "node_modules/path-to-regexp": {
-      "version": "0.1.13",
-      "resolved": "https://registry.npmjs.org/path-to-regexp/-/path-to-regexp-0.1.13.tgz",
-      "integrity": "sha512-A/AGNMFN3c8bOlvV9RreMdrv7jsmF9XIfDeCd87+I8RNg6s78BhJxMu69NEMHBSJFxKidViTEdruRwEk/WIKqA==",
-      "license": "MIT"
-    },
     "node_modules/picomatch": {
       "version": "2.3.1",
       "license": "MIT",