Expand project documentation

[code-by-sia]

Summary

• Expands README documentation links and fixes the sample .ows URL.
• Adds more complete development, architecture, user guide, and supported format documentation.
• Adds a troubleshooting guide for Vite base-path, dependency, test, build-warning, and GitHub Pages asset issues.

Closes #58.

Verification

• npm test
• npm run typecheck
• npm run build

Note: npm run build still reports the existing direct eval warning in src/lib/core/formula/Evaluator.ts; build succeeds.