feat: render graph explorer zone boundaries

tests/test_graph_explorer.py

@@ -399,6 +399,9 @@ def test_registry_serves_graph_explorer_exports(tmp_path: Path) -> None:
         assert 'id="mode-select"' in page
         assert 'id="layout-select"' in page
         assert 'id="label-select"' in page
+        assert 'id="zone-overlay"' in page
+        assert 'id="zone-boundary-toggle"' in page
+        assert 'id="zone-group-select"' in page
         assert 'id="node-type-filter"' in page
         assert 'id="edge-type-filter"' in page
         assert 'id="rule-panel"' in page
@@ -411,6 +414,14 @@ def test_registry_serves_graph_explorer_exports(tmp_path: Path) -> None:
         assert "ruleActionFor" in page
         assert "ruleRemovalSignature" in page
         assert "zoneModeFields" in page
+        assert "zoneForData" in page
+        assert "zoneBoundsForNodes" in page
+        assert "renderZoneOverlay" in page
+        assert "renderZoneDetails" in page
+        assert "dev-tegwick" in page
+        assert 'normalized === "staging"' in page
+        assert "zoneBoundaries" in page
+        assert "zoneGrouping" in page
         assert "renderMapOverview" in page
         assert "route without policy authority" in page
         assert "deploymentEnvironment" in page