T6641: Add vyos-network-event-logger Service

The service parses and logs network events for improved monitoring and diagnostics.
Supported event types include:

- `RTM_NEWROUTE`, `RTM_DELROUTE`
- `RTM_NEWLINK`, `RTM_DELLINK`
- `RTM_NEWADDR`, `RTM_DELADDR`
- `RTM_NEWNEIGH`, `RTM_DELNEIGH`, `RTM_GETNEIGH`
- `RTM_NEWRULE`, `RTM_DELRULE`

Added operational mode commands for filtered log retrieval:
- `show log network-event <event-type> <interface>`: Retrieve logs filtered by event type and interface.
- `show interfaces <type> <name> event-log <event-type>`: Display interface-specific logs filtered by event type.

1 files changed, 18 insertions, 0 deletions

diff --git a/python/vyos/include/uapi/linux/icmpv6.py b/python/vyos/include/uapi/linux/icmpv6.py
new file mode 100644
index 000000000..47e0c723c
--- /dev/null
+++ b/python/vyos/include/uapi/linux/icmpv6.py
@@ -0,0 +1,18 @@
+# Copyright (C) 2025 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+ICMPV6_ROUTER_PREF_LOW = 3
+ICMPV6_ROUTER_PREF_MEDIUM = 0
+ICMPV6_ROUTER_PREF_HIGH = 1
+ICMPV6_ROUTER_PREF_INVALID = 2