refactor: extract messaging client into top-level messaging folder

Move messaging_client.nim and the delivery_service machinery (send/recv
services, processors, not_delivered_storage) out of waku/ and waku/node/
into a dedicated top-level messaging/ folder.

The delivery services are a messaging-layer concern built on top of the
node, not part of node core, so a sibling folder makes that boundary
explicit. Shared message types (waku/api/types) and the node-owned
subscription_manager are left in place to avoid churn on widely-imported
modules.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

channels/reliable_channel.nim

@@ -21,7 +21,7 @@ import stew/byteutils
 import libp2p/crypto/crypto as libp2p_crypto
 
 import waku/api/types
-import waku/node/delivery_service/send_service
+import messaging/delivery_service/send_service
 import waku/waku_core/topics
 
 import ./events

channels/reliable_channel_manager.nim

@@ -13,7 +13,7 @@ import stew/byteutils
 import brokers/broker_context
 
 import waku/events/message_events as waku_message_events
-import waku/messaging_client
+import messaging/messaging_client
 import waku/waku_core/topics
 
 import ./reliable_channel

messaging/delivery_service/not_delivered_storage/migrations.nim

@@ -1,7 +1,7 @@
 {.push raises: [].}
 
 import std/[tables, strutils, os], results, chronicles
-import ../../../common/databases/db_sqlite, ../../../common/databases/common
+import waku/common/databases/db_sqlite, waku/common/databases/common
 
 logScope:
   topics = "waku node delivery_service"

messaging/delivery_service/not_delivered_storage/not_delivered_storage.nim

@@ -9,9 +9,7 @@
 
 import results
 import
-  ../../../common/databases/db_sqlite,
-  ../../../waku_core/message/message,
-  ../../../node/delivery_service/not_delivered_storage/migrations
+  waku/common/databases/db_sqlite, waku/waku_core/message/message, ./migrations
 
 const NotDeliveredMessagesDbUrl = "not-delivered-messages.db"
 

messaging/messaging_client.nim

@@ -1,14 +1,10 @@
 import results, chronos
 import chronicles
 import
-  ./api/types,
-  ./node/[
-    waku_node,
-    subscription_manager,
-    delivery_service/recv_service,
-    delivery_service/send_service,
-    delivery_service/send_service/delivery_task,
-  ]
+  waku/api/types,
+  waku/node/[waku_node, subscription_manager],
+  messaging/delivery_service/[recv_service, send_service],
+  messaging/delivery_service/send_service/delivery_task
 
 type MessagingClient* = ref object
   node: WakuNode

tests/api/test_api_receive.nim

@@ -6,7 +6,8 @@ import libp2p/[peerid, peerinfo, crypto/crypto]
 import brokers/broker_context
 import ../testlib/[common, wakucore, wakunode, testasync]
 import ../waku_archive/archive_utils
-import waku/messaging_client
+import messaging/messaging_client
+import messaging/delivery_service/recv_service
 
 import
   waku,
@@ -17,7 +18,6 @@ import
     waku_relay/protocol,
     waku_archive,
     waku_archive/common as archive_common,
-    node/delivery_service/recv_service,
   ]
 import waku/factory/waku_conf
 import tools/confutils/cli_args

tests/api/test_api_subscription.nim

@@ -5,7 +5,7 @@ import chronos, testutils/unittests, stew/byteutils
 import libp2p/[peerid, peerinfo, multiaddress, crypto/crypto]
 import brokers/broker_context
 import ../testlib/[common, wakucore, wakunode, testasync]
-import waku/messaging_client
+import messaging/messaging_client
 
 import
   waku,

tests/node/test_wakunode_health_monitor.nim

@@ -15,7 +15,6 @@ import
     node/health_monitor/protocol_health,
     node/health_monitor/topic_health,
     node/health_monitor/node_health_monitor,
-    messaging_client,
     node/waku_node/relay,
     node/waku_node/store,
     node/waku_node/lightpush,
@@ -27,6 +26,7 @@ import
 
 import ../testlib/[wakunode, wakucore], ../waku_archive/archive_utils
 import waku/node/subscription_manager
+import messaging/messaging_client
 
 const MockDLow = 4 # Mocked GossipSub DLow value
 

waku/api/api.nim

@@ -1,9 +1,9 @@
 import chronicles, chronos, results
 
 import waku/factory/waku
-import waku/messaging_client
+import messaging/messaging_client
 import waku/[requests/health_requests, waku_core, waku_node]
-import waku/node/delivery_service/send_service
+import messaging/delivery_service/send_service
 import waku/node/subscription_manager
 import libp2p/peerid
 import ../../tools/confutils/cli_args

waku/factory/waku.nim

@@ -30,7 +30,6 @@ import
     waku_enr/sharding,
     waku_enr/multiaddr,
     api/types,
-    messaging_client,
     common/logging,
     node/peer_manager,
     node/health_monitor,
@@ -50,6 +49,7 @@ import
     persistency/persistency,
   ],
   channels/reliable_channel_manager,
+  messaging/messaging_client,
   ./waku_conf,
   ./waku_state_info