iceberg: wire pagination for list namespaces/tables REST APIs (#8275)

* s3api/iceberg: wire list pagination tokens and page size

* fmt

* Update weed/s3api/iceberg/iceberg.go

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

weed/s3api/iceberg/iceberg_pagination_test.go

@@ -0,0 +1,69 @@
+package iceberg
+
+import (
+	"net/http/httptest"
+	"testing"
+)
+
+func TestParsePaginationDefaultValues(t *testing.T) {
+	req := httptest.NewRequest("GET", "/v1/namespaces", nil)
+
+	pageToken, pageSize, err := parsePagination(req)
+	if err != nil {
+		t.Fatalf("parsePagination() error = %v", err)
+	}
+	if pageToken != "" {
+		t.Fatalf("pageToken = %q, want empty", pageToken)
+	}
+	if pageSize != defaultListPageSize {
+		t.Fatalf("pageSize = %d, want %d", pageSize, defaultListPageSize)
+	}
+}
+
+func TestParsePaginationUsesCamelCaseParameters(t *testing.T) {
+	req := httptest.NewRequest("GET", "/v1/namespaces?pageToken=abc&pageSize=25", nil)
+
+	pageToken, pageSize, err := parsePagination(req)
+	if err != nil {
+		t.Fatalf("parsePagination() error = %v", err)
+	}
+	if pageToken != "abc" {
+		t.Fatalf("pageToken = %q, want %q", pageToken, "abc")
+	}
+	if pageSize != 25 {
+		t.Fatalf("pageSize = %d, want %d", pageSize, 25)
+	}
+}
+
+func TestParsePaginationSupportsHyphenatedFallback(t *testing.T) {
+	req := httptest.NewRequest("GET", "/v1/namespaces?page-token=abc&page-size=17", nil)
+
+	pageToken, pageSize, err := parsePagination(req)
+	if err != nil {
+		t.Fatalf("parsePagination() error = %v", err)
+	}
+	if pageToken != "abc" {
+		t.Fatalf("pageToken = %q, want %q", pageToken, "abc")
+	}
+	if pageSize != 17 {
+		t.Fatalf("pageSize = %d, want %d", pageSize, 17)
+	}
+}
+
+func TestParsePaginationRejectsInvalidPageSize(t *testing.T) {
+	testCases := []string{
+		"/v1/namespaces?pageSize=0",
+		"/v1/namespaces?pageSize=-1",
+		"/v1/namespaces?pageSize=foo",
+		"/v1/namespaces?pageSize=1001",
+	}
+
+	for _, rawURL := range testCases {
+		t.Run(rawURL, func(t *testing.T) {
+			req := httptest.NewRequest("GET", rawURL, nil)
+			if _, _, err := parsePagination(req); err == nil {
+				t.Fatalf("parsePagination() expected error for url %q", rawURL)
+			}
+		})
+	}
+}