[misc] Move shared components to shared directory (#4286)

Moved the following directories:

```
  - management/client → shared/management/client
  - management/domain → shared/management/domain
  - management/proto → shared/management/proto
  - signal/client → shared/signal/client
  - signal/proto → shared/signal/proto
  - relay/client → shared/relay/client
  - relay/auth → shared/relay/auth
```

and adjusted import paths

shared/management/domain/validate_test.go

@@ -0,0 +1,185 @@
+package domain
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestValidateDomains(t *testing.T) {
+	tests := []struct {
+		name     string
+		domains  []string
+		expected List
+		wantErr  bool
+	}{
+		{
+			name:     "Empty list",
+			domains:  nil,
+			expected: nil,
+			wantErr:  true,
+		},
+		{
+			name:     "Valid ASCII domain",
+			domains:  []string{"sub.ex-ample.com"},
+			expected: List{"sub.ex-ample.com"},
+			wantErr:  false,
+		},
+		{
+			name:     "Valid Unicode domain",
+			domains:  []string{"münchen.de"},
+			expected: List{"xn--mnchen-3ya.de"},
+			wantErr:  false,
+		},
+		{
+			name:     "Valid Unicode, all labels",
+			domains:  []string{"中国.中国.中国"},
+			expected: List{"xn--fiqs8s.xn--fiqs8s.xn--fiqs8s"},
+			wantErr:  false,
+		},
+		{
+			name:     "With underscores",
+			domains:  []string{"_jabber._tcp.gmail.com"},
+			expected: List{"_jabber._tcp.gmail.com"},
+			wantErr:  false,
+		},
+		{
+			name:     "Invalid domain format",
+			domains:  []string{"-example.com"},
+			expected: nil,
+			wantErr:  true,
+		},
+		{
+			name:     "Invalid domain format 2",
+			domains:  []string{"example.com-"},
+			expected: nil,
+			wantErr:  true,
+		},
+		{
+			name:     "Multiple domains valid and invalid",
+			domains:  []string{"google.com", "invalid,nbdomain.com", "münchen.de"},
+			expected: List{"google.com"},
+			wantErr:  true,
+		},
+		{
+			name:     "Valid wildcard domain",
+			domains:  []string{"*.example.com"},
+			expected: List{"*.example.com"},
+			wantErr:  false,
+		},
+		{
+			name:     "Wildcard with dot domain",
+			domains:  []string{".*.example.com"},
+			expected: nil,
+			wantErr:  true,
+		},
+		{
+			name:     "Wildcard with dot domain",
+			domains:  []string{".*.example.com"},
+			expected: nil,
+			wantErr:  true,
+		},
+		{
+			name:     "Invalid wildcard domain",
+			domains:  []string{"a.*.example.com"},
+			expected: nil,
+			wantErr:  true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := ValidateDomains(tt.domains)
+			assert.Equal(t, tt.wantErr, err != nil)
+			assert.Equal(t, got, tt.expected)
+		})
+	}
+}
+
+func TestValidateDomainsList(t *testing.T) {
+	validDomains := make([]string, maxDomains)
+	for i := range maxDomains {
+		validDomains[i] = fmt.Sprintf("example%d.com", i)
+	}
+
+	tests := []struct {
+		name    string
+		domains []string
+		wantErr bool
+	}{
+		{
+			name:    "Empty list",
+			domains: nil,
+			wantErr: false,
+		},
+		{
+			name:    "Single valid ASCII domain",
+			domains: []string{"sub.ex-ample.com"},
+			wantErr: false,
+		},
+		{
+			name:    "Underscores in labels",
+			domains: []string{"_jabber._tcp.gmail.com"},
+			wantErr: false,
+		},
+		{
+			// Unlike ValidateDomains (which converts to punycode),
+			// ValidateDomainsStrSlice will fail on non-ASCII domain chars.
+			name:    "Unicode domain fails (no punycode conversion)",
+			domains: []string{"münchen.de"},
+			wantErr: true,
+		},
+		{
+			name:    "Invalid domain format - leading dash",
+			domains: []string{"-example.com"},
+			wantErr: true,
+		},
+		{
+			name:    "Invalid domain format - trailing dash",
+			domains: []string{"example-.com"},
+			wantErr: true,
+		},
+		{
+			name:    "Multiple domains with a valid one, then invalid",
+			domains: []string{"google.com", "invalid_domain.com-"},
+			wantErr: true,
+		},
+		{
+			name:    "Valid wildcard domain",
+			domains: []string{"*.example.com"},
+			wantErr: false,
+		},
+		{
+			name:    "Wildcard with leading dot - invalid",
+			domains: []string{".*.example.com"},
+			wantErr: true,
+		},
+		{
+			name:    "Invalid wildcard with multiple asterisks",
+			domains: []string{"a.*.example.com"},
+			wantErr: true,
+		},
+		{
+			name:    "Exactly maxDomains items (valid)",
+			domains: validDomains,
+			wantErr: false,
+		},
+		{
+			name:    "Exceeds maxDomains items",
+			domains: append(validDomains, "extra.com"),
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := ValidateDomainsList(tt.domains)
+			if tt.wantErr {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+			}
+		})
+	}
+}