fix: keep CARP state knowledge out of the base package (4.10.1)

carp_virtual_ip() and its state table are CARP protocol knowledge; under the
agreed structure (PR #37, docs/STRUCTURE.md) the base package carries only
contracts, data shapes and I/O-free reconcilers. They move to the driver that
speaks CARP (napalm-opnsense). The contract stays: VirtualIpsDict.carp and
VirtualIpDict.holds.

Nothing used the helper yet; it was released in 4.10.0 an hour ago.

netOrk #1121.

README.md

@@ -128,13 +128,12 @@ A mechanism it could not read completely is `None` ("did not look"), a host with
 `[]`. The command is about 4 kB, so a driver sends it on an exec channel
 (`_run_virtual_ips_command(command, privileged=)`), not typed into a shell.
 
-A firewall's CARP addresses are a third mechanism, `carp`, which a firewall driver reads
-from its own API and reports under the reading's `carp` key (`vip_manager` and
-`keepalived` then None). `carp_virtual_ip(...)` turns one address bound to a VHID into the
-entry -- the same for OPNsense and pfSense. Unlike the other two, a CARP entry says who
-holds the address (`holds`): every member carries the address in its configuration, and a
-firewall's interface list need not show it, but CARP's state names the MASTER. A state it
-does not know leaves `holds` None, and the caller falls back on the interfaces.
+A firewall's CARP addresses are a third mechanism, `carp`: a firewall driver reads them from
+its own API and reports them under the reading's `carp` key (`vip_manager` and `keepalived`
+then None). What a CARP state means is protocol knowledge and stays in that driver. The
+contract only carries the result: unlike the other two, a CARP entry says who holds the
+address (`holds`), because a firewall's interface list need not show it. `holds` None
+leaves the holder to the interfaces.
 
 `SystemIdentityMixin` (`get_system_identity`) reads a host's SMBIOS identity -- system UUID,
 product serial and board serial from `/sys/class/dmi/id` -- which is what ties a server to