docs: add project move notice to doc site homepage

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: prosdev

website/content/index.mdx

@@ -11,6 +11,10 @@ Local semantic code search for Cursor and Claude Code via MCP.
 
 [Get Started](/docs) · [View on GitHub](https://github.com/prosdevlab/dev-agent)
 
+<Callout type="warning">
+  **Project moved.** dev-agent started as a hack project at [Lytics](https://github.com/lytics/dev-agent) and is now maintained independently at [prosdevlab/dev-agent](https://github.com/prosdevlab/dev-agent). All future development happens here.
+</Callout>
+
 <Callout type="info">
   **New in v{latestVersion.version}** — {latestVersion.summary} [See what's new →](/updates)
 </Callout>