feat: locale routing (en flat, zh subfolder), language switcher, dark default

- Derive lang from folder (posts/zh/* -> zh, else en); remove lang: frontmatter
- Change post route to [...slug] to capture nested zh paths
- Add nav language switcher (EN <-> 中文) + /zh/ landing page
- Default theme to dark (light opt-in via toggle)
- Translate hello-world-zh placeholder into English intro post
- Update case study: docker-compose sample + real install gotchas (commit history)
- Add docs/project-state.md (Tier 1/2/3 backlog)

src/pages/categories/[category].astro

@@ -2,16 +2,17 @@
 import BaseLayout from '../../layouts/BaseLayout.astro';
 import PostList from '../../components/PostList.astro';
 import { getCollection } from 'astro:content';
+import { isEn } from '../../lib/lang';
 
 export async function getStaticPaths() {
-  const posts = await getCollection('posts', ({ data }) => !data.draft && data.lang === 'en');
+  const posts = await getCollection('posts', isEn);
   const cats = [...new Set(posts.map((p) => p.data.category))];
   return cats.map((cat) => ({ params: { category: cat } }));
 }
 
 const { category } = Astro.params;
 
-const posts = (await getCollection('posts', ({ data }) => !data.draft && data.lang === 'en'))
+const posts = (await getCollection('posts', isEn))
   .filter((p) => p.data.category === category)
   .sort((a, b) => b.data.pubDate.valueOf() - a.data.pubDate.valueOf());
 ---

src/pages/categories/index.astro

@@ -1,8 +1,9 @@
 ---
 import BaseLayout from '../../layouts/BaseLayout.astro';
 import { getCollection } from 'astro:content';
+import { isEn } from '../../lib/lang';
 
-const posts = await getCollection('posts', ({ data }) => !data.draft && data.lang === 'en');
+const posts = await getCollection('posts', isEn);
 
 const categories = [...new Set(posts.map((p) => p.data.category))].sort();
 

src/pages/index.astro

@@ -2,9 +2,10 @@
 import BaseLayout from '../layouts/BaseLayout.astro';
 import PostList from '../components/PostList.astro';
 import { getCollection } from 'astro:content';
+import { isEn } from '../lib/lang';
 import { SITE } from '../config';
 
-const posts = (await getCollection('posts', ({ data }) => !data.draft && data.lang === 'en'))
+const posts = (await getCollection('posts', isEn))
   .sort((a, b) => b.data.pubDate.valueOf() - a.data.pubDate.valueOf());
 ---
 

src/pages/posts/[...slug].astro

@@ -2,6 +2,7 @@
 import BaseLayout from '../../layouts/BaseLayout.astro';
 import AuthorCard from '../../components/AuthorCard.astro';
 import { getCollection, render } from 'astro:content';
+import { postLang } from '../../lib/lang';
 
 export async function getStaticPaths() {
   const posts = await getCollection('posts', ({ data }) => !data.draft);
@@ -14,17 +15,19 @@ export async function getStaticPaths() {
 const { post } = Astro.props;
 const { Content } = await render(post);
 
+const lang = postLang(post.slug);
+
 // Reading time (~200 wpm)
 const words = post.body?.trim().split(/\s+/).length ?? 0;
 const minutes = Math.max(1, Math.round(words / 200));
 
 const fmt = (d: Date) =>
-  d.toLocaleDateString('en-US', { year: 'numeric', month: 'long', day: 'numeric' });
+  d.toLocaleDateString(lang === 'zh' ? 'zh-CN' : 'en-US', { year: 'numeric', month: 'long', day: 'numeric' });
 
-// Related posts: same category or overlapping tags, excluding self
+// Related posts: same language, same category or overlapping tags, excluding self
 const all = await getCollection('posts', ({ data }) => !data.draft);
 const related = all
-  .filter((p) => p.slug !== post.slug && p.data.lang === post.data.lang)
+  .filter((p) => p.slug !== post.slug && postLang(p.slug) === lang)
   .map((p) => {
     const catMatch = p.data.category === post.data.category ? 2 : 0;
     const tagOverlap = p.data.tags.filter((t) => post.data.tags.includes(t)).length;
@@ -39,7 +42,7 @@ const related = all
 <BaseLayout
   title={`${post.data.title} — Mr Hoelee`}
   description={post.data.description}
-  lang={post.data.lang}
+  lang={lang}
   ogImage={post.data.ogImage ?? '/og-default.png'}
   type="article"
   article={{
@@ -69,7 +72,7 @@ const related = all
 
   {related.length > 0 && (
     <section class="related">
-      <h2>Related posts</h2>
+      <h2>{lang === 'zh' ? '相关文章' : 'Related posts'}</h2>
       <div class="related-grid">
         {related.map((p) => (
           <a class="related-card" href={`/posts/${p.slug}/`}>

src/pages/posts/index.astro

@@ -2,8 +2,9 @@
 import BaseLayout from '../../layouts/BaseLayout.astro';
 import PostList from '../../components/PostList.astro';
 import { getCollection } from 'astro:content';
+import { isEn } from '../../lib/lang';
 
-const posts = (await getCollection('posts', ({ data }) => !data.draft && data.lang === 'en'))
+const posts = (await getCollection('posts', isEn))
   .sort((a, b) => b.data.pubDate.valueOf() - a.data.pubDate.valueOf());
 ---
 

src/pages/rss.xml.ts

@@ -1,9 +1,10 @@
 import rss from '@astrojs/rss';
 import { getCollection } from 'astro:content';
+import { isEn } from '../lib/lang';
 import { SITE } from '../config';
 
 export async function GET(context) {
-  const posts = (await getCollection('posts', ({ data }) => !data.draft && data.lang === 'en'))
+  const posts = (await getCollection('posts', isEn))
     .sort((a, b) => b.data.pubDate.valueOf() - a.data.pubDate.valueOf());
 
   return rss({

src/pages/zh/index.astro

@@ -0,0 +1,39 @@
+---
+import BaseLayout from '../../layouts/BaseLayout.astro';
+import PostList from '../../components/PostList.astro';
+import { getCollection } from 'astro:content';
+import { isZh } from '../../lib/lang';
+import { SITE } from '../../config';
+
+const posts = (await getCollection('posts', isZh))
+  .sort((a, b) => b.data.pubDate.valueOf() - a.data.pubDate.valueOf());
+---
+
+<BaseLayout
+  title={`${SITE.handle} — 技术博客`}
+  description="Hoelee 的技术博客中文版：工程、DevOps、自托管、AI 自动化与 Web3 实验。"
+  lang="zh"
+>
+  <section>
+    <h1>你好，我是 {SITE.author}。</h1>
+    <p>
+      一名base在马来西亚的全栈开发者兼 DevOps 工程师。我构建 Web 应用，
+      自托管一个约 140 个容器的 homelab，并运营面向马来西亚中小企业的
+      邮箱托管业务。这里是博客的中文部分。
+    </p>
+    <p>
+      <a href="/">切换到英文</a>
+      <span class="sep">·</span>
+      <a href="/about/">关于我</a>
+    </p>
+  </section>
+
+  <section>
+    <h2>最新文章</h2>
+    {posts.length === 0 ? (
+      <p><em>中文文章即将发布，敬请期待。</em></p>
+    ) : (
+      <PostList posts={posts} />
+    )}
+  </section>
+</BaseLayout>