feat: add pager support to bd list (bd-jdz3)

Add pager support following gh cli conventions:

Flags:
- --no-pager: disable pager for this command

Environment variables:
- BD_PAGER / PAGER: pager program (default: less)
- BD_NO_PAGER: disable pager globally

Behavior:
- Auto-enable pager when output exceeds terminal height
- Respect LESS env var for pager options
- Disable pager when stdout is not a TTY (pipes/scripts)

Implementation:
- New internal/ui/pager.go with ToPager() function
- Added formatIssueLong/formatIssueCompact helper functions
- Buffer output before displaying to support pager

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/ui/pager_test.go

@@ -0,0 +1,174 @@
+package ui
+
+import (
+	"os"
+	"strings"
+	"testing"
+)
+
+func TestContentHeight(t *testing.T) {
+	tests := []struct {
+		name    string
+		content string
+		want    int
+	}{
+		{
+			name:    "empty string",
+			content: "",
+			want:    0,
+		},
+		{
+			name:    "single line",
+			content: "hello",
+			want:    1,
+		},
+		{
+			name:    "single line with newline",
+			content: "hello\n",
+			want:    2,
+		},
+		{
+			name:    "multiple lines",
+			content: "line1\nline2\nline3",
+			want:    3,
+		},
+		{
+			name:    "multiple lines with trailing newline",
+			content: "line1\nline2\nline3\n",
+			want:    4,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := contentHeight(tt.content)
+			if got != tt.want {
+				t.Errorf("contentHeight() = %d, want %d", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestShouldUsePager(t *testing.T) {
+	tests := []struct {
+		name      string
+		opts      PagerOptions
+		envVars   map[string]string
+		wantPager bool
+	}{
+		{
+			name:      "NoPager option set",
+			opts:      PagerOptions{NoPager: true},
+			wantPager: false,
+		},
+		{
+			name:      "BD_NO_PAGER env set",
+			opts:      PagerOptions{NoPager: false},
+			envVars:   map[string]string{"BD_NO_PAGER": "1"},
+			wantPager: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Set up env vars
+			for k, v := range tt.envVars {
+				oldVal := os.Getenv(k)
+				os.Setenv(k, v)
+				defer os.Setenv(k, oldVal)
+			}
+
+			got := shouldUsePager(tt.opts)
+			if got != tt.wantPager {
+				t.Errorf("shouldUsePager() = %v, want %v", got, tt.wantPager)
+			}
+		})
+	}
+}
+
+func TestGetPagerCommand(t *testing.T) {
+	tests := []struct {
+		name     string
+		envVars  map[string]string
+		wantPager string
+	}{
+		{
+			name:      "default pager",
+			envVars:   map[string]string{},
+			wantPager: "less",
+		},
+		{
+			name:      "BD_PAGER set",
+			envVars:   map[string]string{"BD_PAGER": "more"},
+			wantPager: "more",
+		},
+		{
+			name:      "PAGER set",
+			envVars:   map[string]string{"PAGER": "cat"},
+			wantPager: "cat",
+		},
+		{
+			name:      "BD_PAGER takes precedence over PAGER",
+			envVars:   map[string]string{"BD_PAGER": "more", "PAGER": "cat"},
+			wantPager: "more",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Save and clear relevant env vars
+			oldBdPager := os.Getenv("BD_PAGER")
+			oldPager := os.Getenv("PAGER")
+			os.Unsetenv("BD_PAGER")
+			os.Unsetenv("PAGER")
+			defer func() {
+				if oldBdPager != "" {
+					os.Setenv("BD_PAGER", oldBdPager)
+				}
+				if oldPager != "" {
+					os.Setenv("PAGER", oldPager)
+				}
+			}()
+
+			// Set up env vars for test
+			for k, v := range tt.envVars {
+				os.Setenv(k, v)
+			}
+
+			got := getPagerCommand()
+			if got != tt.wantPager {
+				t.Errorf("getPagerCommand() = %q, want %q", got, tt.wantPager)
+			}
+		})
+	}
+}
+
+func TestToPagerNoPagerOption(t *testing.T) {
+	// Create a test output that we want to capture
+	content := "test content\n"
+
+	// With NoPager=true, ToPager should just print directly
+	// (we can't easily capture stdout in a test, but we can verify no error)
+	err := ToPager(content, PagerOptions{NoPager: true})
+	if err != nil {
+		t.Errorf("ToPager() returned error: %v", err)
+	}
+}
+
+func TestToPagerWithBdNoPagerEnv(t *testing.T) {
+	oldVal := os.Getenv("BD_NO_PAGER")
+	os.Setenv("BD_NO_PAGER", "1")
+	defer func() {
+		if oldVal != "" {
+			os.Setenv("BD_NO_PAGER", oldVal)
+		} else {
+			os.Unsetenv("BD_NO_PAGER")
+		}
+	}()
+
+	content := strings.Repeat("line\n", 100)
+	err := ToPager(content, PagerOptions{})
+	if err != nil {
+		t.Errorf("ToPager() returned error: %v", err)
+	}
+}