cleanup: remove old unused tooling and reference configs

Remove:
- @lhci/cli + lighthouserc.cjs (Lighthouse CI, never used in CI pipeline)
- @playwright/test + e2e/ tests + playwright.config.ts (E2E tests not used)
- setup/ directory (emulator/nitro reference install configs)
- Build artifacts: .next.prev/, coverage/, backups/

package.json

@@ -18,10 +18,6 @@
 		"knip": "knip",
 		"analyze": "ANALYZE=true pnpm build",
 		"test": "vitest run",
-		"test:e2e": "playwright test",
-		"lhci:collect": "lhci collect",
-		"lhci:assert": "lhci assert",
-		"lhci:server": "lhci server",
 		"db:migrate": "tsx scripts/apply-migrations.ts",
 		"db:migrate:status": "tsx scripts/apply-migrations.ts --status",
 		"jobs:worker": "tsx scripts/jobs-worker.ts",
@@ -79,9 +75,7 @@
 	},
 	"devDependencies": {
 		"@biomejs/biome": "2.5.6",
-		"@lhci/cli": "^0.15.1",
 		"@next/bundle-analyzer": "^16.2.12",
-		"@playwright/test": "1.62.0",
 		"@tailwindcss/forms": "^0.5.11",
 		"@tailwindcss/postcss": "^4.3.3",
 		"@tailwindcss/typography": "^0.5.20",