chore: add ESLint config, root package.json, and fix type import ordering

[Geliogabalus]

Summary

• Add root eslint.config.mjs with shared ESLint flat config for JS and TS files across all demos
• Add root package.json with lint, build, and screenshot scripts, plus ESLint devDependencies
• Fix type import ordering across 252 TypeScript files (regular imports before type imports)
• Update README.md with a Root Scripts section documenting the new npm scripts
• Add GitHub Actions workflow that runs ESLint on every non-draft PR and blocks merging on lint errors

Details

eslint.config.mjs

• Covers .js, .jsx, .mjs and .ts, .tsx, .mts files
• Uses @typescript-eslint/eslint-plugin flat config preset (flat/recommended)
• Enforces 4-space indent, single quotes, semicolons, prefer-const, consistent-type-imports
• Ignores .github/, build/, dist/, node_modules/

Type import ordering

• Reordered imports in 252 TS/TSX files so import type statements always follow regular import statements
• Files with intentional section comments were left untouched

.github/workflows/lint.yml

• Triggers on PR open, sync, reopen, and ready-for-review events
• Skips draft PRs — only runs when the PR is marked as ready
• Runs npm run lint; a non-zero exit blocks merging

Test plan

• Run npm install at the repo root
• Run npm run lint — should report no errors
• Open a draft PR and confirm the lint workflow does not run
• Mark the PR as ready and confirm the lint workflow runs and passes
• Spot-check a few TS files to confirm type imports appear after regular imports

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