add 'point your coding agent here' callout on the landing page

A tip admonition under the intro telling devs to point their coding agent
at the handbook for awareness of our libs/standards/deploy rules, with
copy-pasteable agent prompts in two tabs: from the live site, or from a
git clone of the repo.

Verified in-browser: tabs switch, prompts + clone command render, copy
buttons present; mkdocs build --strict clean.

Signed-off-by: disqualifier <dev@disqualifier.me>

docs/index.md

@@ -7,6 +7,32 @@ This is a public site — it documents generic patterns and conventions. Real
 infrastructure specifics (hostnames, internal IPs, exact topology, secrets) stay
 out of it; examples use placeholders like `<dev>`, `<project>`, and `/srv/...`.
 
+!!! tip "Point your coding agent here"
+    Want your agent aware of our libraries, standards, and deploy rules before it
+    writes a line? Tell it to read this handbook — so it reaches for an existing
+    `rethink-public` lib instead of reinventing it, follows our conventions, and
+    builds a deploy-ready container.
+
+    === "From the live site"
+
+        ```text
+        Read https://docs.rethinkstudios.io and follow it: prefer our
+        rethink-public libraries, match our coding standards, and make anything
+        deployable per the deploy guide.
+        ```
+
+    === "From git"
+
+        ```bash
+        git clone git@git.rethinkstudios.io:rethink-public/handbook.git
+        ```
+
+        ```text
+        Read the markdown under ./handbook/docs and follow it: prefer our
+        rethink-public libraries, match our coding standards, and make anything
+        deployable per the deploy guide.
+        ```
+
 ## Sections
 
 <div class="grid cards" markdown>