Split Debian package into vpp-maglevd + vpp-maglev; add maglevt.1 manpage

vpp-maglevd ships maglevd, maglevd-frontend, both systemd units, and
the config conffiles. vpp-maglev ships maglevc and maglevt as pure
client tools so jump hosts and workstations can install them without
pulling in the daemon. pkg-deb now emits four .debs per release
(2 packages x 2 archs); build-deb.sh takes a package-name argument
and dispatches accordingly.

debian/vpp-maglev.control.in

@@ -0,0 +1,22 @@
+Package: vpp-maglev
+Version: @VERSION@
+Architecture: @ARCH@
+Maintainer: Pim van Pelt <pim@ipng.ch>
+Section: net
+Priority: optional
+Description: Maglev CLI client and out-of-band VIP tester
+ maglevc is an interactive CLI client for maglevd with tab completion,
+ inline help, and a one-shot mode for scripting. It talks to maglevd
+ over gRPC and can drive either a local daemon or a remote one.
+ .
+ maglevt is an out-of-band HTTP probe TUI that reads a maglev.yaml,
+ hits each configured frontend on a configurable HTTP path, and
+ reports latency plus a response-header tally so operators can see
+ Maglev failover as it happens. It does not talk gRPC and does not
+ depend on a running maglevd; it is useful for validating a maglevd
+ restart end-to-end from a client perspective and for debugging pool
+ failover.
+ .
+ Install alongside the vpp-maglevd package to manage a local daemon,
+ or install standalone on a jump host or operator workstation to
+ manage remote maglevds over gRPC.