The manual as a site: a landing page, the chapters, and a page per module

index.sz is a landing page pointing to the manual, now manual.sz, and to
modules/, where each library module has a page made by @generate-docs from
the docs it was compiled with. The chapters gain appendices, and part III
links each module to its page. glasnost's page cache is ignored.

🤖 Generated with [ECA](https://eca.dev) (anthropic/claude-opus-5-5)

Co-Authored-By: eca-agent <git@eca.dev>

manual.sz

@@ -0,0 +1,13 @@
+(meta (title "The Bjolang manual")
+      (date "2026-09-29"))
+
+@toc[#:depth 3]
+
+@include["_01.Language-basics.sz"]
+@include["_02_.Writing-programs.sz"]
+@include["_03.Standard-library.sz"]
+@include["_04.Appendices.sz"]
+
+@subsection{std/random}
+
+@defmodule[(std random)]