refactor(constants): restructure constant definitions

[github-actions]

Closes #556

Applied changes based on Issue #556.

I’ve refactored src/constants.ts to improve readability and consistency while preserving all existing functionality:

• Added explicit type annotations for all constants (string/number) to match the style in other constant files.
• Reorganized and grouped related constants in a logical order (trigger, timeout, workspace, progress) with clear JSDoc blocks.
• Cleaned up JSDoc formatting (multi‑line comments) for consistency.
• Left the LOADING_PHRASES re‑export unchanged except for doc formatting.

All exports remain identical so there are no breaking changes. Let me know if you’d like any further tweaks!