Add fakes CLI (cmd/fakes); document it README-first with an SQL template example

cmd/fakes/main.go

@@ -0,0 +1,61 @@
+// Command fakes prints one fake value from a locale directory.
+//
+//	fakes ./locales/sv_SE person        # a full person
+//	fakes ./locales/sv_SE person.last   # just the surname (dotted path)
+//	fakes -seed 42 ./locales/sv_SE address
+//
+// It is a thin CLI over the fakes library: New(dir) then Fake(path).
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/Timewave-AB/fakes"
+)
+
+const usage = `Usage: fakes [-seed N] <locale-dir> <path>
+
+  <locale-dir>  a locale directory, e.g. ./locales/sv_SE
+  <path>        a category, or a dotted path into one (person, person.last)
+  -seed N       seed for reproducible output`
+
+func main() { os.Exit(run(os.Args[1:], os.Stdout, os.Stderr)) }
+
+// run is main's testable core: it returns the process exit code (0 ok, 1
+// runtime error, 2 misuse) and writes only to the given streams.
+func run(args []string, stdout, stderr io.Writer) int {
+	fs := flag.NewFlagSet("fakes", flag.ContinueOnError)
+	fs.SetOutput(stderr)
+	fs.Usage = func() { fmt.Fprintln(stderr, usage) }
+	seed := fs.Uint64("seed", 0, "seed for reproducible output")
+	if err := fs.Parse(args); err != nil {
+		return 2
+	}
+	if fs.NArg() != 2 {
+		fs.Usage()
+		return 2
+	}
+
+	var opts []fakes.Option
+	fs.Visit(func(fl *flag.Flag) {
+		if fl.Name == "seed" {
+			opts = append(opts, fakes.WithSeed(*seed))
+		}
+	})
+
+	f, err := fakes.New(fs.Arg(0), opts...)
+	if err != nil {
+		fmt.Fprintln(stderr, err)
+		return 1
+	}
+	v, err := f.Fake(fs.Arg(1))
+	if err != nil {
+		fmt.Fprintln(stderr, err)
+		return 1
+	}
+	fmt.Fprintln(stdout, v)
+	return 0
+}