docs: Add JSDoc comments to core API functions

[Mattis44]

Description

Add JSDoc documentation comments to the main API functions in src/core.ts and src/hooks/useCommandPalette.ts

Why

This helps new developers understand the codebase and improves IDE autocomplete support for users.

What to do

1. Review the functions in src/core.ts and src/hooks/useCommandPalette.ts
2. Add JSDoc comments following the existing style
3. Include @param, @returns, and @example tags where applicable
4. Test that TypeScript shows the comments in your IDE

Example

/**
 * Opens the command palette
 * @returns void
 * @example
 * const { open } = useCommandPalette();
 * open();
 */
function open() { ... }

Labels

good first issue, documentation, help wanted