port: rewrite bootstrap tool in Go

Replace the Python bootstrap script with a Go implementation that
cross-compiles to native binaries for Linux and macOS on x86_64 and
aarch64. The Go port preserves all sections of the original (system
packages, optional Flatpak GUI apps, custom downloads, and the macOS
firecracker VM bridge) and adds first-class pacman support so the tool
works on Arch-family distros alongside Debian, RHEL, and macOS.

A Makefile produces a host binary via `make build` and the full
four-target matrix under dist/ via `make build-all`.

issues.go

@@ -0,0 +1,74 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"time"
+)
+
+// Issue log accumulated over the run; written to bootstrap_run.log at the end
+// when there's something to report.
+
+var (
+	issuesMu sync.Mutex
+	issues   []string
+	notices  []string
+)
+
+func logIssue(level, msg string) {
+	issuesMu.Lock()
+	defer issuesMu.Unlock()
+	fmt.Printf("  [%s] %s\n", level, msg)
+	issues = append(issues, fmt.Sprintf("[%s] %s", level, msg))
+}
+
+func warn(msg string)   { logIssue("WARN", msg) }
+func errLog(msg string) { logIssue("ERROR", msg) }
+
+func notice(msg string) {
+	issuesMu.Lock()
+	defer issuesMu.Unlock()
+	notices = append(notices, msg)
+}
+
+func runLogPath() string {
+	exe, err := os.Executable()
+	if err != nil {
+		return "bootstrap_run.log"
+	}
+	return filepath.Join(filepath.Dir(exe), "bootstrap_run.log")
+}
+
+func writeRunLog() {
+	issuesMu.Lock()
+	defer issuesMu.Unlock()
+	if len(issues) == 0 {
+		fmt.Println("\nNo issues — log file not written.")
+		return
+	}
+	path := runLogPath()
+	ts := time.Now().Format("2006-01-02 15:04:05")
+	lines := []string{fmt.Sprintf("# Bootstrap run — %s", ts), ""}
+	lines = append(lines, issues...)
+	content := strings.Join(lines, "\n") + "\n"
+	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+		fmt.Fprintf(os.Stderr, "failed to write run log: %v\n", err)
+		return
+	}
+	fmt.Printf("\n%d issue(s) logged to: %s\n", len(issues), path)
+}
+
+func printNotices() {
+	issuesMu.Lock()
+	defer issuesMu.Unlock()
+	if len(notices) == 0 {
+		return
+	}
+	fmt.Println("\nNotices:")
+	for _, n := range notices {
+		fmt.Printf("  • %s\n", n)
+	}
+}