Seed from go-template-repo, renamed to simplexcalc

The template's files at a77fd30, without its history or LICENSE, after
script/rename simplexcalc.

Model: opus-5-5

templates/templates.go

@@ -0,0 +1,18 @@
+// Package templates carries the HTML templates and partials into the
+// binary. It holds no logic: internal/render owns parsing and
+// execution, and this exists only so the embed directive sits next to
+// the files it embeds.
+package templates
+
+import "embed"
+
+// FS holds every page template and partial.
+//
+// A file that is not matched here does not exist at runtime, and the
+// failure is a 500 at request time rather than a build error — so the
+// patterns are deliberately whole-directory, and internal/render parses
+// all of them at startup so that a broken template fails the process
+// instead of one request.
+//
+//go:embed *.html partials/*.html
+var FS embed.FS