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/rss.xml.js

@@ -1,11 +1,9 @@
 import rss from '@astrojs/rss';
-import { getCollection } from 'astro:content';
 import { SITE } from '../consts';
+import { getPublishedPosts } from '../utils/posts';
 
 export async function GET(context) {
-  const posts = (await getCollection('blog', ({ data }) => !data.draft)).sort(
-    (a, b) => b.data.pubDate.valueOf() - a.data.pubDate.valueOf()
-  );
+  const posts = await getPublishedPosts();
 
   return rss({
     title: SITE.title,