mopac-pdf v0: markdown to beautiful PDFs via digest-pinned typst

Go CLI that turns the markdown currency of this stack (Redmine notes,
Discourse posts, briefing output) into typeset PDFs: two embedded typst
templates (report with title page/TOC/headers, dense brief), front-matter
(title/subtitle/author/date/classification/template), GFM tables, and
bar charts rendered in pure Go (go-chart) from fenced chart data blocks.
Engine is a prebuilt typst 0.15.1 container pinned by digest and run
--network none; PDF bytes to stdout or -o. Exit codes 0/1/2.

All dev in docker (dev.sh/Makefile); unit tests + golden typst fixtures
plus a host-side smoke against the real engine container.

Generated with Crush

Assisted-by: Crush:glm-5.2

templates/templates.go

@@ -0,0 +1,52 @@
+// Package templates embeds the shipped typst templates so the mopac-pdf
+// binary is self-contained: the engine container only ever sees the
+// prepared compile root.
+package templates
+
+import (
+	"embed"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+//go:embed *.typ
+var embedded embed.FS
+
+// Names lists the shipped template names ("report", "brief").
+func Names() []string {
+	entries, err := embedded.ReadDir(".")
+	if err != nil {
+		return nil
+	}
+	var names []string
+	for _, e := range entries {
+		if !e.IsDir() && strings.HasSuffix(e.Name(), ".typ") {
+			names = append(names, strings.TrimSuffix(e.Name(), ".typ"))
+		}
+	}
+	return names
+}
+
+// Source returns the template source for name: from dir when set (custom
+// template drop-in), else the embedded copy.
+func Source(dir, name string) (string, error) {
+	if strings.ContainsAny(name, `/\.`) || name == "" {
+		return "", fmt.Errorf("template: invalid name %q", name)
+	}
+	if dir != "" {
+		data, err := os.ReadFile(filepath.Join(dir, name+".typ"))
+		if err == nil {
+			return string(data), nil
+		}
+		if !os.IsNotExist(err) {
+			return "", err
+		}
+	}
+	data, err := embedded.ReadFile(name + ".typ")
+	if err != nil {
+		return "", fmt.Errorf("template %q not found (shipped: %s)", name, strings.Join(Names(), ", "))
+	}
+	return string(data), nil
+}