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

vendor/github.com/wcharczuk/go-chart/v2/fileutil.go

@@ -0,0 +1,49 @@
+package chart
+
+import (
+	"bufio"
+	"io"
+	"os"
+)
+
+// ReadLines reads a file and calls the handler for each line.
+func ReadLines(filePath string, handler func(string) error) error {
+	f, err := os.Open(filePath)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		line := scanner.Text()
+		err = handler(line)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// ReadChunks reads a file in `chunkSize` pieces, dispatched to the handler.
+func ReadChunks(filePath string, chunkSize int, handler func([]byte) error) error {
+	f, err := os.Open(filePath)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	chunk := make([]byte, chunkSize)
+	for {
+		readBytes, err := f.Read(chunk)
+		if err == io.EOF {
+			break
+		}
+		readData := chunk[:readBytes]
+		err = handler(readData)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}