Fix PPR empty generateStaticParams error and update dependencies

- Add placeholder fallback to generateStaticParams for cacheComponents compatibility
- Update npm packages within semver range (next 16.1.6, react 19.2.4, shiki 3.22.0, etc.)
- Add /new-post skill for blog publishing workflow
- Update CLAUDE.md with git remote mirroring docs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude/commands/new-post.md

@@ -0,0 +1,63 @@
+# New Blog Post
+
+Create and publish a new blog post for the personal blog.
+
+## Step 1: Gather Information
+
+Ask the user for the following using AskUserQuestion (all in one prompt):
+
+1. **Title** — the article title (Chinese or English)
+2. **Tags** — offer existing tags from past posts as multi-select options: `Medicine - 醫學`, `Writings - 創作`, `Hardware - 硬體`, `Software - 軟體`, `Unboxing - 開箱`. User can also input custom tags.
+3. **Feature image** — options: no image, provide a URL or Unsplash link, or provide a local file path
+4. **Description** — short excerpt for SEO/article list, or skip for now
+
+## Step 2: Create the Post File
+
+Create the markdown file at `content/posts/<title>.md` with this frontmatter format:
+
+```yaml
+---
+title: <title>
+slug: <english-slug-derived-from-title>
+published_at: '<current-ISO-date>'
+description: <description if provided>
+tags:
+- <tag1>
+- <tag2>
+authors:
+- Gbanyan
+feature_image: ../assets/<slug>.jpg
+---
+```
+
+If the user provides article content, add it after the frontmatter.
+
+## Step 3: Handle Feature Image
+
+If the user provides an Unsplash URL:
+1. Extract the real image URL by running: `curl -sL "<unsplash-page-url>" | grep -oE 'https://images\.unsplash\.com/photo-[^"? ]+' | head -1`
+2. Download at 1920px width: `curl -sL -o content/assets/<slug>.jpg "<image-url>?w=1920&q=90"`
+3. Optimize with jpegoptim: `jpegoptim --max=85 --strip-all --all-progressive content/assets/<slug>.jpg`
+4. Verify the image visually using the Read tool
+
+If the user provides a local file path, copy it to `content/assets/<slug>.jpg` and optimize.
+
+If no image, omit `feature_image` from frontmatter.
+
+## Step 4: Preview (Optional)
+
+Ask the user if they want to preview with `npm run dev` before publishing.
+
+## Step 5: Publish
+
+Execute the two-step deployment:
+
+```bash
+# 1. Commit and push content submodule
+git -C content add . && git -C content commit -m "Add new post: <title>" && git -C content push
+
+# 2. Update main repo submodule pointer and push (triggers CI/CD)
+git add content && git commit -m "Update content submodule" && git push
+```
+
+Confirm both pushes succeeded. The CI/CD pipeline on git.gbanyan.net will handle deployment automatically (and crontab mirrors to gitea.gbanyan.net).