feat: scaffold calepin website

Assisted-by: Delta:zai-glm-5.3

site/404.typ

@@ -0,0 +1,7 @@
+#import "@preview/calepin:0.1.7": *
+
+#show: page-layout.with(title: "Not Found")
+
+= 404
+
+Page not found.

site/calepin.toml

@@ -0,0 +1,17 @@
+title = "Yggdrasil"
+description = "Knowledge Base"
+theme = "calepin"
+
+pdf = false
+
+[static]
+include = ["assets/**"]
+
+[sidebar]
+fold = false
+
+[[sidebar.section]]
+title = "Start"
+  [[sidebar.section.item]]
+  target = "index.typ"
+

site/index.typ

@@ -0,0 +1,7 @@
+#import "@preview/calepin:0.1.7": *
+
+#show: page-layout.with(title: "Yggdrasil")
+
+= Yggdrasil
+
+Welcome to Yggdrasil, the central knowledge base.