v1.0.0 — first release

Bump VERSION to 1.0.0 and cut the first tagged release of vpp-maglev.

Also in this commit:

- maglevc: MAGLEV_SERVER env var as an alternative to the --server
  flag, matching the MAGLEV_CONFIG / MAGLEV_GRPC_ADDR convention on
  the other binaries. The flag takes precedence when both are set.
- Rename cmd/maglevd -> cmd/server and cmd/maglevc -> cmd/client so
  the source directory names are decoupled from binary names (the
  frontend and tester commands already followed this convention).
  Build outputs and the Debian packages are unchanged.

README.md

@@ -93,7 +93,7 @@ doesn't kill the daemon; `SIGTERM` / `SIGINT` remain the clean
 shutdown signals.
 
 Every flag on every binary also has an environment-variable
-equivalent (e.g. `MAGLEV_CONFIG`, `MAGLEV_GRPC_ADDR`,
+equivalent (e.g. `MAGLEV_CONFIG`, `MAGLEV_GRPC_ADDR`, `MAGLEV_SERVER`,
 `MAGLEV_SERVERS`, `MAGLEV_LISTEN`, `MAGLEV_LOG_LEVEL`) so all three
 programs can be driven entirely via env in containerized
 deployments.