Replace the deprecated via_device with via_device_id

Home Assistant 2026.9 deprecates the `via_device` (domain, identifier)
tuple in favour of `via_device_id`, which takes the parent device's
registry id; `via_device` stops working in 2027.8.0.

Register the hub device explicitly in async_setup_entry before the
platforms are forwarded, so the per-identity entities can look it up and
pass its `.id`. The hub device info moves into a shared helper so both
call sites describe the same device.

custom_components/reticulum/entity.py

@@ -4,7 +4,11 @@ from __future__ import annotations
 
 from homeassistant.config_entries import ConfigEntry, ConfigSubentry
 from homeassistant.core import callback
-from homeassistant.helpers.device_registry import DeviceEntryType, DeviceInfo
+from homeassistant.helpers.device_registry import (
+    DeviceEntryType,
+    DeviceInfo,
+    async_get as async_get_device_registry,
+)
 from homeassistant.helpers.dispatcher import async_dispatcher_connect
 from homeassistant.helpers.entity import Entity
 
@@ -12,6 +16,22 @@ from .const import DOMAIN, identity_signal, stack_signal
 from .reticulum_client import IdentityManager, ReticulumStack
 
 
+def hub_device_info(entry: ConfigEntry) -> DeviceInfo:
+    """Device info for the stack (hub) device.
+
+    Shared with ``async_setup_entry``, which registers this device up front so the
+    per-identity devices can reference it by registry id.
+    """
+    return DeviceInfo(
+        identifiers={(DOMAIN, entry.entry_id)},
+        name="Reticulum",
+        manufacturer="Reticulum Network Stack",
+        model="RNS stack",
+        entry_type=DeviceEntryType.SERVICE,
+        configuration_url="https://reticulum.network/",
+    )
+
+
 class ReticulumStackEntity(Entity):
     """Base for hub (stack-level) entities."""
 
@@ -21,14 +41,7 @@ class ReticulumStackEntity(Entity):
     def __init__(self, stack: ReticulumStack, entry: ConfigEntry) -> None:
         self._stack = stack
         self._entry = entry
-        self._attr_device_info = DeviceInfo(
-            identifiers={(DOMAIN, entry.entry_id)},
-            name="Reticulum",
-            manufacturer="Reticulum Network Stack",
-            model="RNS stack",
-            entry_type=DeviceEntryType.SERVICE,
-            configuration_url="https://reticulum.network/",
-        )
+        self._attr_device_info = hub_device_info(entry)
 
     async def async_added_to_hass(self) -> None:
         self.async_on_remove(
@@ -57,14 +70,21 @@ class ReticulumIdentityEntity(Entity):
         self._manager = manager
         self._entry = entry
         self._subentry = subentry
-        self._attr_device_info = DeviceInfo(
+        device_info = DeviceInfo(
             identifiers={(DOMAIN, subentry.subentry_id)},
             name=subentry.title,
             manufacturer="Reticulum Network Stack",
             model="LXMF identity",
             entry_type=DeviceEntryType.SERVICE,
-            via_device=(DOMAIN, entry.entry_id),
         )
+        # `via_device_id` takes the parent's registry id, not its identifiers, so
+        # look up the hub device registered by async_setup_entry.
+        hub = async_get_device_registry(manager.hass).async_get_device_by_identifier(
+            (DOMAIN, entry.entry_id), entry.entry_id
+        )
+        if hub is not None:
+            device_info["via_device_id"] = hub.id
+        self._attr_device_info = device_info
 
     async def async_added_to_hass(self) -> None:
         self.async_on_remove(