test: add coverage tests across backend + fix mock for PENDING checkout support

New test files cover previously untested paths across DAV, validators,
S3, Square, mw, bookings, user, and payments packages.

Includes mock fix: HoldCheckouts flag on MockClient allows tests to
pause auto-complete goroutine for testing PENDING checkout states.

Coverage: 50.4% → 65.0% (+14.6pp)

backend/internal/logutil/logutil_test.go

@@ -0,0 +1,197 @@
+//go:build test
+
+package logutil
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// NO_COLOR is unset in tests so all ANSI vars are non-empty. The
+// noColor=true path is not testable here because init() runs once at
+// package load time; it would require a separate test binary.
+
+func TestColorVars_AreNotEmpty(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		v    string
+	}{
+		{"Reset", Reset},
+		{"Bold", Bold},
+		{"Dim", Dim},
+		{"Cyan", Cyan},
+		{"Green", Green},
+		{"Red", Red},
+		{"Yellow", Yellow},
+		{"Magenta", Magenta},
+		{"BoldGreen", BoldGreen},
+		{"BoldYellow", BoldYellow},
+		{"BoldRed", BoldRed},
+		{"BoldBlue", BoldBlue},
+		{"BoldMagenta", BoldMagenta},
+		{"DebugLvl", DebugLvl},
+		{"WarnLvl", WarnLvl},
+		{"ErrorLvl", ErrorLvl},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			assert.NotEmpty(t, tt.v, "package var %s should contain ANSI code when NO_COLOR is unset", tt.name)
+		})
+	}
+}
+
+func TestColorVars_StartWithEscape(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		v    string
+	}{
+		{"Reset", Reset},
+		{"Bold", Bold},
+		{"Dim", Dim},
+		{"Cyan", Cyan},
+		{"Green", Green},
+		{"Red", Red},
+		{"Yellow", Yellow},
+		{"Magenta", Magenta},
+		{"BoldGreen", BoldGreen},
+		{"BoldYellow", BoldYellow},
+		{"BoldRed", BoldRed},
+		{"BoldBlue", BoldBlue},
+		{"BoldMagenta", BoldMagenta},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			assert.True(t, tt.v[0] == '\033', "package var %s should start with ESC byte", tt.name)
+		})
+	}
+}
+
+func TestColoredDuration(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		d        time.Duration
+		wantPre  string
+		wantText string
+		wantSuf  string
+	}{
+		{
+			name:     "under_500ms_returns_green",
+			d:        200 * time.Millisecond,
+			wantPre:  Green,
+			wantText: "200ms",
+			wantSuf:  Reset,
+		},
+		{
+			name:     "exactly_499ms_returns_green",
+			d:        499 * time.Millisecond,
+			wantPre:  Green,
+			wantText: "499ms",
+			wantSuf:  Reset,
+		},
+		{
+			name:     "exactly_500ms_returns_yellow",
+			d:        500 * time.Millisecond,
+			wantPre:  Yellow,
+			wantText: "500ms",
+			wantSuf:  Reset,
+		},
+		{
+			name:     "between_500ms_and_5s_returns_yellow",
+			d:        3 * time.Second,
+			wantPre:  Yellow,
+			wantText: "3s",
+			wantSuf:  Reset,
+		},
+		{
+			name:     "exactly_4999ms_returns_yellow",
+			d:        4999 * time.Millisecond,
+			wantPre:  Yellow,
+			wantText: "4.999s",
+			wantSuf:  Reset,
+		},
+		{
+			name:     "exactly_5s_returns_red",
+			d:        5 * time.Second,
+			wantPre:  Red,
+			wantText: "5s",
+			wantSuf:  Reset,
+		},
+		{
+			name:     "over_5s_returns_red",
+			d:        10 * time.Second,
+			wantPre:  Red,
+			wantText: "10s",
+			wantSuf:  Reset,
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			got := ColoredDuration(tt.d)
+			want := tt.wantPre + tt.wantText + tt.wantSuf
+			assert.Equal(t, want, got)
+		})
+	}
+}
+
+func TestColoredRows(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		n        int
+		wantPre  string
+		wantText string
+		wantSuf  string
+	}{
+		{
+			name:     "zero_rows_plural",
+			n:        0,
+			wantPre:  BoldBlue,
+			wantText: "0 rows",
+			wantSuf:  Reset,
+		},
+		{
+			name:     "one_row_singular",
+			n:        1,
+			wantPre:  BoldBlue,
+			wantText: "1 row",
+			wantSuf:  Reset,
+		},
+		{
+			name:     "two_rows_plural",
+			n:        2,
+			wantPre:  BoldBlue,
+			wantText: "2 rows",
+			wantSuf:  Reset,
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			got := ColoredRows(tt.n)
+			want := tt.wantPre + tt.wantText + tt.wantSuf
+			assert.Equal(t, want, got)
+		})
+	}
+}