Update outdated npm tooling

[haan]

Summary

• update ESLint tooling to ESLint 10
• update globals and Vite to current releases
• keep html-to-image pinned at 1.11.11 because newer versions break React Flow export rendering
• remove dead fileText initializers flagged by ESLint 10

Validation

• npm ci
• npm run lint
• npm run test:unit (361 passed)
• npm run build:ci
• npm audit (0 vulnerabilities)
• npm outdated (only html-to-image remains, intentionally pinned)