move cypress into frontend

Manage Cypress through the frontend npm lockfile instead of the Nix shell. Approve its install script and align the Oxlint package pair so npm can resolve dependencies without overrides.

ai/frontend-context.md

@@ -20,8 +20,10 @@ The scaffold uses:
 - `src/stores/` for Pinia stores.
 - `@` as an alias for `src/` in both Vite and TypeScript.
 
-There are no views, shared components, API layer, or test setup yet. Do not
-invent an architecture for them before requested behavior establishes one.
+There are no views, shared components, API layer, or configured test suite
+yet. Cypress is installed as a frontend development dependency, but there is
+no Cypress configuration or npm test script. Do not invent an architecture
+before requested behavior establishes one.
 
 ## Package management and commands
 
@@ -97,7 +99,8 @@ under `dist/` is generated and ignored.
 
 ## Testing
 
-No frontend test runner or test script is configured yet.
+Cypress is installed, but no frontend test configuration or test script
+exists yet.
 
 - Do not invent test commands or claim frontend tests passed.
 - New frontend behavior must still follow the shared test-first workflow.

flake.nix

@@ -37,7 +37,6 @@
             nodejs
             nixfmt
             nixfmt-tree
-            cypress
             yaml-language-server
             typescript
             postgresql

frontend/website/package.json

@@ -26,14 +26,15 @@
     "@vitejs/plugin-vue-jsx": "^5.1.6",
     "@vue/eslint-config-typescript": "^14.9.0",
     "@vue/tsconfig": "^0.9.1",
+    "cypress": "^15.19.0",
     "eslint": "^10.7.0",
     "eslint-config-prettier": "^10.1.8",
-    "eslint-plugin-oxlint": "~1.73.0",
+    "eslint-plugin-oxlint": "~1.76.0",
     "eslint-plugin-vue": "~10.9.2",
     "jiti": "^2.7.0",
     "npm-run-all2": "^9.0.2",
     "oxfmt": "^0.59.0",
-    "oxlint": "~1.74.0",
+    "oxlint": "~1.76.0",
     "typescript": "~6.0.0",
     "vite": "^8.1.5",
     "vite-plugin-vue-devtools": "^8.1.5",
@@ -42,5 +43,8 @@
   },
   "engines": {
     "node": "^22.18.0 || >=24.12.0"
+  },
+  "allowScripts": {
+    "cypress@15.19.0": true
   }
 }