Dashboard: add @types/node so the Docker dashboard-build stage compiles (#24)

The Docker `dashboard-build` stage installs ONLY the dashboard
workspace's deps and runs tsc --noEmit. Locally and in CI's validate
job the dashboard tsc walked UP from dashboard/node_modules to find
the root's @types/node — both workspaces share a parent filesystem.
Inside Docker, /app/dashboard/node_modules is in isolation and there
is no /app/node_modules to walk into, so playwright.config.ts and
the test files erupted with TS2591 ("Cannot find name 'process'")
and TS2304 ("Cannot find name 'global'").

The production deploy on main consequently failed at this exact step
right after the dev → main merge fired the Deploy workflow.

Fix:
- Add @types/node ^20 to dashboard devDependencies (matches the root
  pin so the SDK version is identical).
- Add "node" to dashboard/tsconfig.json compilerOptions.types so the
  explicit types list activates the new install.

Verified locally:
- npm --prefix dashboard run typecheck  → clean
- npm --prefix dashboard run build      → 330 KB / 98 KB gzipped, source maps emitted
- docker build --target dashboard-build → succeeds in isolation,
  reproducing the prod deploy path

The dev branch's CI did not catch this because validate runs both
root + dashboard `npm ci` in the same workspace, so root's
@types/node was always reachable. Long-term gap: add a "build via
Docker" check on dev too. Tracked separately.

Author: pulkitpareek18

dashboard/package-lock.json

@@ -29,6 +29,7 @@
     "@testing-library/jest-dom": "^6.9.1",
     "@testing-library/react": "^16.3.2",
     "@testing-library/user-event": "^14.6.1",
+    "@types/node": "^20.19.41",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
     "@vitejs/plugin-react": "^4.7.0",

dashboard/package.json

@@ -15,7 +15,7 @@
     "noUnusedLocals": false,
     "noUnusedParameters": false,
     "noFallthroughCasesInSwitch": true,
-    "types": ["vitest/globals", "@testing-library/jest-dom"]
+    "types": ["node", "vitest/globals", "@testing-library/jest-dom"]
   },
   "include": ["src", "vite.config.ts", "playwright.config.ts", "e2e"]
 }