feat: add YouTube video embed to Flying on the Command Line chapter

CLAUDE.md

@@ -22,7 +22,7 @@ Contains: typography rules, format conversions, validation checklist.
 
 ### Before Making Changes
 
-1. Run `make serve` to start the dev server (port 3745 = ESHL on dialpad)
+1. Start the dev server with `npx docusaurus start --port 3745` (`make serve` may not exist)
 2. Load the appropriate skill(s)
 3. Check the sidebar structure in `sidebars.js`
 
@@ -35,17 +35,22 @@ Contains: typography rules, format conversions, validation checklist.
 ### Git Workflow
 
 - **Never commit directly to main** - Always use feature branches
+- **Never force push** - Accumulate commits; PRs use squash merge
 - **Always ask before pushing** - Get explicit user confirmation
 - Run build before commits to catch errors early
 
-## Migration Work
+## Content Patterns
 
 When editing any file in `docs/`:
 
 1. Load `/skill effective-shell-migration`
 2. Follow typography rules (em-dashes `—` not `---`)
 3. Use validation checklist before committing
-4. Check for common mistakes:
+4. Image captions use `*italic text*` on the line below the image
+5. Web-only sections use `## <WebsiteOnly />Section Title`
+6. YouTube embeds use `<iframe>` directly (no component), place inline where relevant
+7. Clean the `build/` directory before building if a previous build exists
+8. Check for common mistakes:
    - Triple hyphens instead of em-dashes
    - Missing `:::note` admonitions
    - Code blocks without language specifiers

docs/01-core-skills/01-fly-on-the-command-line/index.mdx

@@ -9,9 +9,9 @@ import Caret from '@site/src/components/Caret/Caret';
 
 Being able to rapidly move around the shell and manipulate text on the command line is critical to being an effective shell user. As you spend more time in the shell and start composing larger and more complex commands, it's especially important that you can work efficiently. In this chapter, we'll look at some techniques to help you do just that. Before long, you'll be navigating the command line at lightning speed.
 
-Below is a quick reference showing the key shortcuts covered in this chapter:
+If you'd like to see these tricks in action, check out this two-minute video:
 
-[![Command line shortcuts quick reference](./images/command-line.png)](https://github.com/dwmkerr/effective-shell)
+<iframe width="560" height="315" src="https://www.youtube.com/embed/xkEFEbGqgaE" title="Flying on the Command Line" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
 
 ## Basic Navigation Techniques
 
@@ -492,6 +492,14 @@ There's a great cheat sheet on emacs readline commands at [readline.kablamo.org/
 
 We'll also see *GNU Readline* later on when we talk about writing programs which work well in the shell.
 
+## <WebsiteOnly />Resources
+
+You can download [command-line.png](./images/command-line.png) and use it as a wallpaper:
+
+[![Command line shortcuts quick reference](./images/command-line.png)](./images/command-line.png)
+
+*Command line navigation shortcuts quick reference*
+
 ## Summary
 
 In this chapter, you learned shortcuts for maneuvering your cursor in the shell, which allows you to edit your code quickly and easily. You also saw how to list and search your command history, edit in place with the shell's default text editor, and take advantage of other techniques to work more efficiently on the command line.

ideas.md

@@ -0,0 +1,7 @@
+# Ideas
+
+Improvements to consider for the website.
+
+## Wallpaper Downloads
+
+Each chapter has a quick reference image (e.g. `command-line.png`). These could be improved with higher-resolution versions designed specifically for use as desktop wallpapers, offered as downloadable resources in each chapter's web-only Resources section.