release: 1.1.0: Domain-admin role and internal/web package split

The first MINOR after 1.0.0: send-only DMARC guidance in the panel, AGPL packaging on every page, and an internal split of `internal/web` ahead of domain-admin work. Upgrading runs one SQLite migration (empty defaults; existing DNS guidance is unchanged until you set a report address).
Changed:
  - `internal/web` split into subpackages (`web/view`, `web/auth`, `web/validate`,
Added:
  - panel: DMARC guidance for send-only relays — the suggested `_dmarc` record
  - AGPL packaging hygiene: [NOTICE](NOTICE) names the copyright holder and the
  - [docs/roadmap.md](docs/roadmap.md) — candidate item **visual-style** (panel

Full detail: CHANGELOG.md (1.1.0).

internal/web/auth/ratelimit.go

@@ -0,0 +1,55 @@
+package auth
+
+import (
+	"sync"
+	"time"
+)
+
+// rateLimiter is a simple fixed-window per-key counter used to throttle the
+// setup and login routes (security.md). Keys are client IPs.
+type rateLimiter struct {
+	max    int
+	window time.Duration
+
+	mu      sync.Mutex
+	buckets map[string]*rlBucket
+}
+
+type rlBucket struct {
+	count      int
+	windowEnds time.Time
+}
+
+func newRateLimiter(max int, window time.Duration) *rateLimiter {
+	return &rateLimiter{
+		max:     max,
+		window:  window,
+		buckets: make(map[string]*rlBucket),
+	}
+}
+
+func (r *rateLimiter) Allow(key string) bool {
+	now := time.Now()
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	b := r.buckets[key]
+	if b == nil || now.After(b.windowEnds) {
+		r.buckets[key] = &rlBucket{count: 1, windowEnds: now.Add(r.window)}
+		r.sweep(now)
+		return true
+	}
+	if b.count >= r.max {
+		return false
+	}
+	b.count++
+	return true
+}
+
+func (r *rateLimiter) sweep(now time.Time) {
+	for k, b := range r.buckets {
+		if now.After(b.windowEnds) {
+			delete(r.buckets, k)
+		}
+	}
+}