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/soft_delete_test.go

@@ -14,7 +14,7 @@ import (
 // TestSoftDelete_Cascade triggers `POST /api/v1/user/account/delete`
 // with X-User-ID set (mirroring what gateway does after authenticated
 // verification) and asserts:
-//   - the account fetch through the authenticated gRPC surface
+//   - the account fetch through the authenticated edge surface
 //     subsequently fails because soft-delete revoked the session;
 //   - the admin geo endpoint reports the user has no remaining
 //     country counter rows.
@@ -57,7 +57,7 @@ func TestSoftDelete_Cascade(t *testing.T) {
 		t.Fatalf("soft delete: status %d body=%s", resp.StatusCode, string(raw))
 	}
 
-	// Authenticated gRPC must now be rejected.
+	// Authenticated edge must now be rejected.
 	deadline := time.Now().Add(2 * time.Second)
 	var lastErr error
 	for time.Now().Before(deadline) {