feat(bookstack-api-cpg): implement PagesService List and Get

Implement PagesService.List with pagination and Get with full page
content including HTML/Markdown fields. Add mock server tests.

pages_test.go

@@ -0,0 +1,77 @@
+package bookstack
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"net/http"
+	"testing"
+)
+
+func TestPagesService_List(t *testing.T) {
+	c := testClient(t, func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/api/pages" {
+			t.Errorf("path = %s, want /api/pages", r.URL.Path)
+		}
+		json.NewEncoder(w).Encode(map[string]any{
+			"data": []map[string]any{
+				{"id": 1, "name": "Page One", "book_id": 1},
+				{"id": 2, "name": "Page Two", "book_id": 1},
+			},
+			"total": 2,
+		})
+	})
+
+	pages, err := c.Pages.List(context.Background(), nil)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(pages) != 2 {
+		t.Fatalf("got %d pages, want 2", len(pages))
+	}
+	if pages[0].Name != "Page One" {
+		t.Errorf("pages[0].Name = %q, want %q", pages[0].Name, "Page One")
+	}
+}
+
+func TestPagesService_Get(t *testing.T) {
+	c := testClient(t, func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/api/pages/5" {
+			t.Errorf("path = %s, want /api/pages/5", r.URL.Path)
+		}
+		json.NewEncoder(w).Encode(map[string]any{
+			"id":      5,
+			"name":    "Test Page",
+			"book_id": 1,
+			"html":    "<p>Content</p>",
+		})
+	})
+
+	page, err := c.Pages.Get(context.Background(), 5)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if page.ID != 5 {
+		t.Errorf("ID = %d, want 5", page.ID)
+	}
+	if page.HTML != "<p>Content</p>" {
+		t.Errorf("HTML = %q", page.HTML)
+	}
+}
+
+func TestPagesService_Get_NotFound(t *testing.T) {
+	c := testClient(t, func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+		json.NewEncoder(w).Encode(map[string]any{
+			"error": map[string]string{"message": "Page not found"},
+		})
+	})
+
+	_, err := c.Pages.Get(context.Background(), 999)
+	if err == nil {
+		t.Fatal("expected error")
+	}
+	if !errors.Is(err, ErrNotFound) {
+		t.Error("expected ErrNotFound")
+	}
+}