chore(deps): update and reorganise dependencies
- Bumped dev dependencies (SvelteKit, Vite, ESLint, Tailwind, etc.)
- Updated various `@esbuild` and `@rollup` packages to latest versions
- Moved `@tailwindcss/nesting` to devDependencies
- Refreshed `remark` and `sanitize-html` versions
- Removed outdated packages and redundant versions