fix: use monocart for e2e coverage to align line counts with vitest

c8's default v8-to-istanbul produces inflated line counts (e.g. 212 vs
57 for the same file) because it maps all source lines including types
and imports. monocart-coverage-reports uses AST analysis to count only
executable lines, producing line counts within 1-3 of vitest's output.
This enables proper Codecov merging of unit + e2e coverage.

Author: kasperpeulen

package.json

@@ -25,7 +25,7 @@
 		"storybook": "turbo watch storybook --filter=@storybook/mcp-internal-storybook",
 		"test": "vitest",
 		"test:ci": "NODE_V8_COVERAGE=./e2e-coverage vitest run --coverage --reporter=default --reporter=github-actions --reporter=junit --outputFile=test-report.junit.xml",
-		"test:ci:report-e2e-coverage": "c8 report --src ./packages --all --exclude-after-remap -n '**/src/**/*.{ts,tsx}' -r lcov --temp-directory ./e2e-coverage -o ./e2e-coverage-report",
+		"test:ci:report-e2e-coverage": "c8 report --experimental-monocart --temp-directory ./e2e-coverage -r lcov -o ./e2e-coverage-report && node -e \"const fs=require('fs'),p='./e2e-coverage-report/lcov.info';fs.writeFileSync(p,fs.readFileSync(p,'utf8').split('end_of_record\\n').filter(s=>/^SF:.+\\/src\\/.+\\.tsx?$/m.test(s)).join('end_of_record\\n')+'end_of_record\\n')\"",
 		"test:run": "vitest run",
 		"turbo": "turbo",
 		"turbo:test": "turbo run test",
@@ -43,6 +43,7 @@
 		"@types/node": "20.19.0",
 		"@vitest/coverage-v8": "4.0.6",
 		"c8": "^10.1.3",
+		"monocart-coverage-reports": "^2.12.9",
 		"oxfmt": "^0.27.0",
 		"oxlint": "^1.25.0",
 		"oxlint-tsgolint": "^0.4.0",