Initial commit: DNS Test - DNS health checking tool

Go backend (miekg/dns) + Nuxt 3 frontend (Tailwind CSS v4).

8 check categories, 52 checks total:
- Overview: @ record, WWW, MX with ASN/provider lookup
- Domain Registration: expiry, registrar (RDAP + whois fallback)
- Parent Delegation: NS records, glue, consistency
- Nameservers: 17 checks (reachability, auth, recursion, TCP/UDP, AXFR, etc.)
- SOA: serial consistency, timing values
- Mail (MX): 11 checks (CNAME, PTR, public IPs, consistency)
- Mail Auth: SPF, DKIM, DMARC
- WWW: A record, CNAME

Features:
- SSE streaming (results appear as each category completes)
- SQLite history (modernc.org/sqlite)
- Rate limiting, CORS, request logging
- Dark mode, responsive design

backend/go.mod

@@ -0,0 +1,16 @@
+module github.com/intodns/backend
+
+go 1.22
+
+require (
+	github.com/miekg/dns v1.1.62
+	modernc.org/sqlite v1.34.5
+)
+
+require (
+	golang.org/x/mod v0.18.0 // indirect
+	golang.org/x/net v0.27.0 // indirect
+	golang.org/x/sync v0.7.0 // indirect
+	golang.org/x/sys v0.22.0 // indirect
+	golang.org/x/tools v0.22.0 // indirect
+)