Panel redesign, per-server I1 masking, node minimum version 0.5.0, installer output

- UI: settings tab with sections (server, API keys, Prometheus, audit, migrate,
  about); server settings moved there; master keys table rework (menu, chips,
  version, compact phone cards); three-state node version chip
- I1: random per-server template (DNS / QUIC Initial / STUN) kept in users.db,
  GET/POST /api/masking, change from the master keys banner
- Hub rejects nodes older than 0.5.0 (close 4026), /ui/nodes reports outdated
- install.sh: spinner for long commands (full output in the log), step progress
  bar, cards; installs older than 0.5.0 require a full reinstall with data reset
- Bump to Beta 0.5.0

internal/ctrl/i1_test.go

@@ -0,0 +1,58 @@
+package ctrl
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestGenI1Templates(t *testing.T) {
+	seen := map[string]bool{}
+	for i := 0; i < 500; i++ {
+		v := GenI1()
+		b, ok := i1Bytes(v)
+		if !ok {
+			t.Fatalf("шаблон не разбирается: %q", v)
+		}
+		kind, label := DescribeI1(v)
+		seen[kind] = true
+		switch kind {
+		case "dns":
+			if !strings.HasPrefix(v, "<r 2>") || !strings.HasPrefix(label, "DNS-запрос к ") {
+				t.Fatalf("DNS: %q → %q", v, label)
+			}
+		case "quic":
+			if n := len(b); n != 1200 && n != 1250 && n != 1252 {
+				t.Fatalf("QUIC длиной %d: %q", n, v)
+			}
+		case "stun":
+			if len(b) != 20 && len(b) != 28 {
+				t.Fatalf("STUN длиной %d: %q", len(b), v)
+			}
+		default:
+			t.Fatalf("неожиданный вид %q: %q", kind, v)
+		}
+		// Только <b>/<r>, без пробелов вне тегов — так I1 пишут и клиенты AmneziaVPN.
+		if strings.Contains(strings.NewReplacer("<b ", "", "<r ", "").Replace(v), " ") {
+			t.Fatalf("лишние пробелы: %q", v)
+		}
+	}
+	for _, k := range []string{"dns", "quic", "stun"} {
+		if !seen[k] {
+			t.Fatalf("шаблон %s ни разу не выпал", k)
+		}
+	}
+}
+
+func TestDescribeI1(t *testing.T) {
+	cases := map[string]string{
+		DefaultParams().I1: "DNS-ответ от icloud.com",
+		"":                 "без маскировки",
+		"<c><t>":           "свой шаблон",
+		"<b 0xdeadbeef>":   "свой шаблон",
+	}
+	for in, want := range cases {
+		if _, got := DescribeI1(in); got != want {
+			t.Errorf("DescribeI1(%q) = %q, want %q", in, got, want)
+		}
+	}
+}