Fix naming inconsistencies

Several naming inconsistencies across the codebase.

File Names

• src/lib/Fun/pinball.svelte - should be PascalCase ( Pinball.svelte)
• src/lib/svg-icons/LinkedIn.svelte - should follow *Icon.svelte convention

Prop Names

Some components use snake_case props instead of camelCase:

• CallToAction.svelte - button_text, button_link
• CallToAction-black.svelte - button_text, button_link
• PostPreview.svelte - post_title, post_link, cover_src, etc.

CSS Typo

• CallToAction-black.svelte:23 - CSS class desctiption should be description