restructure handbook to flat-page spec

Replace the four-section dir layout with the revised flat-page spec:
- Three-page nav: Libraries, Standards, Deploy.
- libraries.md: live client-side fetch of the rethink-public org from the
  Gitea API, denylist-filtered, sorted table linking each repo, no version
  pins, graceful fallback on fetch/CORS failure.
- standards.md: house coding standards.
- deploy.md: deploy guide for rethink-net (services uid 1337, uid-agnostic
  Docker, paths/mounts, bind-mount permissions, read-only secrets).
- index.md landing card grid updated for the three sections.
- gitignore Playwright MCP artifacts.

Verified: mkdocs build --strict clean; libraries fallback renders live.
Signed-off-by: disqualifier <dev@disqualifier.me>

docs/index.md

@@ -1,46 +1,35 @@
 # Rethink Studios Handbook
 
-The shared reference for how we build, deploy, and operate. Generic patterns and
-conventions live here — sanitized for public consumption. Real infrastructure
-specifics (hostnames, internal IPs, secrets, exact topology) stay in our private
-runbooks.
+The public reference for building and shipping with Rethink Studios: our shared
+libraries, our coding standards, and how to deploy a project on our network.
+
+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/...`.
 
 ## Sections
 
 <div class="grid cards" markdown>
 
--   :material-rocket-launch: __[Deploy](deploy/index.md)__
+-   :material-package-variant: __[Libraries](libraries.md)__
 
     ---
 
-    How services get from a repo to running behind the proxy — container
-    standards, compose patterns, and step-by-step deploy guides.
+    The live list of the `rethink-public` library suite, pulled straight from
+    Gitea — each entry links to the repo, where the README and tags live.
 
--   :material-ruler-square: __[Conventions](conventions/index.md)__
+-   :material-ruler-square: __[Standards](standards.md)__
 
     ---
 
-    Coding, library, and infrastructure conventions. Naming, layout, logging,
-    and the rules that keep things consistent across projects.
+    House coding standards — file hygiene, docstrings, type hints, linting, and
+    how we handle errors.
 
--   :material-package-variant: __[Libraries](libraries/index.md)__
+-   :material-rocket-launch: __[Deploy](deploy.md)__
 
     ---
 
-    Usage docs for the shared `rethink-public` library suite — what each lib
-    does and how to wire it into a project.
-
--   :material-tools: __[Runbooks](runbooks/index.md)__
-
-    ---
-
-    Operational how-tos for recurring tasks — sanitized for public reference.
+    How to get a project running on **rethink-net** — containers, paths and
+    mounts, permissions, and secrets.
 
 </div>
-
-## Conventions for this handbook
-
-- One topic per page, grouped by section directory.
-- Public means sanitized: use placeholders (`<host>`, `<dev>`, `/srv/...`) and
-  describe the pattern, not our literal infrastructure.
-- Code blocks are tagged with their language and kept copy-pasteable.