Migrate to typescript

[akumm2k]

Summary

This PR:

• adds typescript project equivalent for the previous js scripts (Motivation: allowing complex app logic in the future).
• enforces local typescript style guide.

References

#9

[Copilot]

Pull request overview

This pull request migrates JavaScript code to TypeScript to enable more complex application logic with better type safety. The migration introduces a TypeScript build setup with ESLint, Prettier, and Vite.

Key Changes:

• Converted three JavaScript files (age.js, invert.js, proj-highlighter.js) to TypeScript with type annotations
• Added TypeScript compilation configuration with strict mode enabled
• Introduced constants modules for better code organization and type safety
• Updated HTML script tags to use ES modules from the compiled TypeScript output

Reviewed changes

Copilot reviewed 17 out of 24 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
ts/tsconfig.json	TypeScript compiler configuration with strict mode, but contains invalid options
ts/src/proj_highlighter.ts	Migrated project highlighter with constants, has null checking issues
ts/src/invert.ts	Dark mode toggle implementation with proper null checking
ts/src/age.ts	Age calculation function with improved type safety
ts/src/constants/tools.ts	Tool constants with breaking change (c-sharp → csharp)
ts/src/constants/projects.ts	Project constants with inconsistent naming (camelCase vs kebab-case)
ts/package.json	Dependencies configuration with potentially non-existent versions
ts/eslint.config.mts	ESLint flat config with syntax errors
ts/.prettierrc	Code formatting rules (72-char line width, single quotes)
index.html	Updated script references to use compiled TypeScript modules

Files not reviewed (1)

• ts/package-lock.json: Language not supported

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