add initial Go implementation of arcline-audit

Implements the full site health auditor with four check groups:

  - SSL/TLS (certificate validity, expiry, chain, TLS version, ciphers)

  - HTTP (redirect chain, security headers, response time)

  - DNS (A/AAAA, MX, SPF, DKIM, DMARC, DNSSEC)

  - Infrastructure (CDN detection, common port probes)

Includes CLI with --checks filter, --json and --out flags,

cross-compile Makefile, and GitLab CI pipeline.

Signed-off-by: Blake Ridgway <blake@blakeridgway.com>

internal/report/renderer.go

@@ -0,0 +1,110 @@
+package report
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"strings"
+	"time"
+
+	"arcline-audit/internal/types"
+)
+
+const sectionWidth = 55
+
+// Terminal renders the audit result to the given writer in a human-readable terminal format.
+func Terminal(w io.Writer, result types.AuditResult) {
+	fmt.Fprintf(w, "\n")
+	printSection(w, "SSL", result.SSL.Checks, func() {
+		if result.SSL.Expiry != (time.Time{}) {
+			fmt.Fprintf(w, "  Issuer     %s\n", result.SSL.Issuer)
+			fmt.Fprintf(w, "  Expires    %s (%d days)\n",
+				result.SSL.Expiry.Format("2006-01-02"), result.SSL.DaysLeft)
+			if result.SSL.TLSVersion != "" {
+				fmt.Fprintf(w, "  TLS        %s\n", result.SSL.TLSVersion)
+			}
+		}
+	})
+
+	printSection(w, "HTTP", result.HTTP.Checks, func() {
+		if result.HTTP.FinalURL != "" {
+			fmt.Fprintf(w, "  Final URL  %s\n", result.HTTP.FinalURL)
+		}
+		fmt.Fprintf(w, "  Response   %dms\n", result.HTTP.ResponseTime.Milliseconds())
+	})
+
+	printSection(w, "DNS", result.DNS.Checks, nil)
+	printSection(w, "Infrastructure", result.Infra.Checks, func() {
+		if result.Infra.CDN != "" {
+			fmt.Fprintf(w, "  CDN        %s\n", result.Infra.CDN)
+		}
+		if result.Infra.ASN != "" {
+			fmt.Fprintf(w, "  ASN        %s\n", result.Infra.ASN)
+		}
+		if result.Infra.Org != "" {
+			fmt.Fprintf(w, "  Org        %s\n", result.Infra.Org)
+		}
+	})
+
+	fmt.Fprintf(w, "\n")
+}
+
+// JSON renders the audit result as indented JSON.
+func JSON(w io.Writer, result types.AuditResult) {
+	enc := json.NewEncoder(w)
+	enc.SetIndent("", "  ")
+	enc.Encode(result)
+}
+
+// PlainText renders the audit result as plain text (no ANSI codes).
+func PlainText(w io.Writer, result types.AuditResult) {
+	sections := []struct {
+		name   string
+		checks []types.CheckResult
+	}{
+		{"SSL", result.SSL.Checks},
+		{"HTTP", result.HTTP.Checks},
+		{"DNS", result.DNS.Checks},
+		{"Infrastructure", result.Infra.Checks},
+	}
+
+	fmt.Fprintf(w, "Audit for %s — %s\n\n", result.Domain, result.Time.Format(time.RFC3339))
+
+	for _, sec := range sections {
+		fmt.Fprintf(w, "── %s %s\n", sec.name, strings.Repeat("─", sectionWidth-5-len(sec.name)))
+		for _, c := range sec.checks {
+			fmt.Fprintf(w, "[%s] %s\n", c.Status, c.Message)
+		}
+		fmt.Fprintf(w, "\n")
+	}
+}
+
+func printSection(w io.Writer, name string, checks []types.CheckResult, extra func()) {
+	header := fmt.Sprintf("── %s ", name)
+	fmt.Fprintf(w, "  %s%s\n", header, strings.Repeat("─", sectionWidth-len(header)-2))
+
+	for _, c := range checks {
+		prefix := statusPrefix(c.Status)
+		fmt.Fprintf(w, "  %s %s\n", prefix, c.Message)
+	}
+
+	if extra != nil {
+		extra()
+	}
+}
+
+func statusPrefix(s types.Status) string {
+	switch s {
+	case types.StatusOK:
+		return "[OK]  "
+	case types.StatusWarn:
+		return "[WARN]"
+	case types.StatusFail:
+		return "[FAIL]"
+	case types.StatusInfo:
+		return "[INFO]"
+	default:
+		return "[????]"
+	}
+}
+