Convert theme JavaScript to TypeScript

[YvetteNikolov]

The theme was originally written in plain JavaScript by design:

• Faster onboarding for juniors at the time
• JavaScript allowed faster development speed (which aligned with Yard's core strength)
• The theme contained minimal JavaScript so TypeScript felt unnecessary

Meanwhile, all shared and critical packages have been written in TypeScript, making the theme an exception rather than the norm.

Now, the situation has changed:

• TypeScript is the standard and easier to onboard than before (with the help of AI)
• The lack of typing hurts code quality
• Having JS in the theme while everything else is TS is inconsistent
• At this point not using TypeScript here looks outdated and unprofessional

Decision: We should migrate all theme JavaScript to TypeScript.

[YvetteNikolov]

Er staat een Draft PR openv an Lara: #35

Wat er nog aangepast moet worden:

• TS config
• @WordPress dependencies TS error, niet hoeven te installeren (want het komt uit de wp global)
• Soms meldingen: Could not find a declaration file for module '@yardinternet/gutenberg-components'.
• Error: Parsing error: Cannot find module '@babel/preset-react’
• Er gaan ook nog dingen fout bij tsx files in de block-variations