Add video thumbnail and update docs

Include a new video-thumbnail.jpg and embed a linked thumbnail in README.md pointing to the demo video. Update AGENTS.md child DOX index to state no child AGENTS.md files are needed and list root-owned files (README.md, LICENSE, banner.jpg, video-thumbnail.jpg, and root-level docs). These changes add the video asset and clarify the repository's documentation indexing.

AGENTS.md

@@ -80,4 +80,5 @@ When the user requests a durable behavior change, record it here or in the relev
 
 ## Child DOX Index
 
-This project is not yet indexed. Before continuing you must scan the project, build the DOX tree and replace this message with the actual index. Go deep and scan files recursively to properly evaluate complexity and create nested DOX files where needed.
+- No child AGENTS.md files are needed for the current repository structure.
+- Root-owned files: `README.md`, `LICENSE`, `banner.jpg`, `video-thumbnail.jpg`, and root-level project documentation.

README.md

@@ -16,6 +16,12 @@ The agent keeps a hierarchy of AGENTS.md files as the project changes:
 
 The result is simple: traverse the docs, understand the local rules, make precise edits, keep the docs current. Less guessing. Less drift. Less "why did it touch that file?"
 
+<p align="center">
+  <a href="https://youtu.be/NVkRkioBXQc">
+    <img src="./video-thumbnail.jpg" alt="Watch: One markdown file just fixed AI coding forever." width="640">
+  </a>
+</p>
+
 ## How to use
 
 1. Copy the contents of [AGENTS.md](./AGENTS.md) into your project's AGENTS.md file.