Migrate Cloudflare Pages uploads off Node 20/refined action

The current Cloudflare Pages upload workflows should move off `AdrianGonz97/refined-cf-pages-action@v1`. Why: - GitHub is deprecating Node 20 for JavaScript actions. Runners begin using Node 24 by default on June 16, 2026, and GitHub says Node 20 will be removed from runners later in fall 2026: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/ - `AdrianGonz97/refined-cf-pages-action` currently declares `runs.using: node20` in `action.yml`: https://github.com/AdrianGonz97/refined-cf-pages-action/blob/main/action.yml - The refined action is an opinionated fork of Cloudflare's Pages action. Cloudflare has archived `cloudflare/pages-action`, marks it deprecated, and recommends `cloudflare/wrangler-action` for Pages deployments: https://github.com/cloudflare/pages-action In this repo, the affected workflows are: - `.github/workflows/deploy-preview.yml` - `.github/workflows/deploy-svelte-4.yml` - `.github/workflows/deploy-tailwind-3.yml` The migration should keep the existing direct-upload behavior, but use `cloudflare/wrangler-action@v3` with `wrangler pages deploy` so the deploy path is no longer blocked by a Node 20 action runtime or by the deprecated Pages action lineage. Related PR: #2736