phase 4: drop stale gRPC nomenclature from integration tests

Phase 4 replaced the gateway's authenticated edge listener with a
Connect-Go HTTP/h2c bootstrap that natively serves Connect, gRPC,
and gRPC-Web. Sweep the integration suite so test names, comments,
and helper docs match the new transport posture: rename
TestUserAccount_GetThroughGatewayGRPC to TestUserAccount_GetThroughGatewayEdge,
flip "authenticated gRPC" / "signed gRPC" / "gateway gRPC" comments
to "authenticated edge", and align testenv doc strings.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

integration/user_profile_update_test.go

@@ -11,7 +11,7 @@ import (
 )
 
 // TestUserProfileUpdate exercises `user.profile.update` over the
-// authenticated gateway gRPC surface and verifies that the new
+// authenticated edge surface (Connect / gRPC / gRPC-Web) and verifies that the new
 // display_name is reflected by a subsequent `user.account.get`.
 func TestUserProfileUpdate(t *testing.T) {
 	plat := testenv.Bootstrap(t, testenv.BootstrapOptions{})