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.

internal/vpp/client.go

@@ -95,7 +95,7 @@ func (c *Client) getStateSource() StateSource {
 // New creates a Client for the given socket paths. The warmup tracker's
 // clock starts here — the restart-neutrality window is measured from the
 // moment the Client is constructed, which in practice is a few tens of
-// milliseconds after process start (see cmd/maglevd/main.go startup
+// milliseconds after process start (see cmd/server/main.go startup
 // sequence). If main.go ever grows a long-running initialisation step
 // before vpp.New(), the warmup clock should be moved accordingly.
 func New(apiAddr, statsAddr string) *Client {