Add date-based post scheduling and daily deploy cron

Gate blog listings/RSS on pubDate<=now (in addition to !draft) via a shared
getPublishedPosts() helper, so a post set to draft:false with a future pubDate
publishes itself once a build runs on that day. Dev shows everything for preview.

Add .gitea/workflows/scheduled-deploy.yml: a daily cron that pings the Coolify
deploy hook so the static site rebuilds and the date gate advances. No file
mutation, no repo write access — needs a runner + COOLIFY_DEPLOY_HOOK secret.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/pages/index.astro

@@ -3,10 +3,9 @@ import BaseLayout from '../layouts/BaseLayout.astro';
 import { Icon } from 'astro-icon/components';
 import { getCollection } from 'astro:content';
 import { SITE } from '../consts';
+import { getPublishedPosts } from '../utils/posts';
 
-const posts = (await getCollection('blog', ({ data }) => !data.draft))
-  .sort((a, b) => b.data.pubDate.valueOf() - a.data.pubDate.valueOf())
-  .slice(0, 4);
+const posts = (await getPublishedPosts()).slice(0, 4);
 
 const fmt = (d: Date) =>
   d.toLocaleDateString(SITE.lang, { year: 'numeric', month: 'short' });