[Lint] Add new lint rule to check backend uses only now() and not new Date()

.oxlint-backend-rules.cjs

@@ -0,0 +1,28 @@
+module.exports = {
+  meta: {
+    name: 'oodikone',
+  },
+  rules: {
+    'no-new-date': {
+      meta: {
+        type: 'suggestion',
+        docs: {
+          description: 'Require the backend clock helper for the current date',
+        },
+        schema: [],
+        messages: {
+          useNow: 'Use now() instead of new Date() so the current time can be controlled in tests.',
+        },
+      },
+      create(context) {
+        return {
+          NewExpression(node) {
+            if (node.callee.type === 'Identifier' && node.callee.name === 'Date' && node.arguments.length === 0) {
+              context.report({ node, messageId: 'useNow' })
+            }
+          },
+        }
+      },
+    },
+  },
+}

.oxlintrc.json

@@ -1,6 +1,7 @@
 {
   "$schema": "./node_modules/oxlint/configuration_schema.json",
   "plugins": ["import", "typescript"],
+  "jsPlugins": ["./.oxlint-backend-rules.cjs"],
   "categories": {
     "correctness": "off"
   },
@@ -36,6 +37,7 @@
   },
   "ignorePatterns": [
     "eslint.config.mjs",
+    ".oxlint-backend-rules.cjs",
     "**/build/**",
     "**/dist/**",
     "**/node_modules/**",
@@ -235,6 +237,13 @@
         "prefer-spread": "error"
       }
     },
+    {
+      "files": ["services/backend/src/**/*.{js,ts,tsx}"],
+      "excludeFiles": ["services/backend/src/util/clock.ts"],
+      "rules": {
+        "oodikone/no-new-date": "error"
+      }
+    },
     {
       "files": ["services/backend/src/routes/*.{ts,js}"],
       "rules": {