Add WatchEvents, enable/disable/weight RPCs, and config check

gRPC / proto
- Rename WatchBackendEvents → WatchEvents; return a stream of Event
  oneof (LogEvent, BackendEvent, FrontendEvent) with optional filter
  flags (log, log_level, backend, frontend)
- Add EnableBackend, DisableBackend, SetFrontendPoolBackendWeight RPCs
- Rename PauseResumeRequest → BackendRequest
- Add CheckConfig RPC returning ok/parse_error/semantic_error

maglevd
- Route slog through a LogBroadcaster (slog.Handler) so WatchEvents
  subscribers can receive structured log records independently of the
  daemon's own --log-level
- Add --reflection flag (default true) to toggle gRPC server reflection
- Add --check flag: validates config file and exits 0/1/2
- SIGHUP: use config.Check before applying reload; log parse vs semantic
  error separately; refuse reload on any error
- Rename default config path /etc/maglev → /etc/vpp-maglev

maglevc
- Add 'watch events [num <n>] [log [level <level>]] [backend] [frontend]'
  command; prints compact protojson, stops on any keypress or Ctrl-C;
  uses cbreak mode (not raw) so output post-processing is preserved
- Add 'set backend <name> enable|disable'
- Add 'set frontend <name> pool <pool> backend <name> weight <0-100>'
- Add 'config check' command

Debian packaging
- Rename service unit to vpp-maglevd.service
- Rename conffiles to /etc/default/vpp-maglev and /etc/vpp-maglev/
- Create maglevd system user/group in postinst; add to vpp group if present
- Add postrm; add adduser to Depends

README.md

@@ -2,55 +2,38 @@
 
 Health checker and gRPC control plane for VPP Maglev load balancing.
 
-## Build
+## Build and Install
 
 ```sh
 make          # builds build/<arch>/maglevd and build/<arch>/maglevc
 make test     # runs all tests
-make proto    # regenerates gRPC stubs from proto/maglev.proto
-make lint     # runs golangci-lint
+make pkg-deb  # Creates a debian package for arm64 and amd64
 ```
 
 Requires Go 1.25+ and (for `make proto`) `protoc` with `protoc-gen-go` and
 `protoc-gen-go-grpc`.
 
-## Debian package
-
-```sh
-make pkg-deb
-```
-
 Produces `vpp-maglev_<version>_amd64.deb` and `vpp-maglev_<version>_arm64.deb`
-in the project root by cross-compiling with `GOOS=linux GOARCH=<arch>`.
+in the `build/` directory by cross-compiling with `GOOS=linux GOARCH=<arch>`.
 Requires `dpkg-deb` (available on any Debian/Ubuntu host).
 
-The package installs:
-
-| Path | Content |
-|---|---|
-| `/usr/sbin/maglevd` | Health-checker daemon |
-| `/usr/bin/maglevc` | Interactive CLI client |
-| `/lib/systemd/system/maglevd.service` | systemd unit |
-| `/etc/default/maglev` | Environment file for the unit (conffile) |
-| `/etc/maglev/maglev.yaml` | Example configuration file (conffile) |
-| `/usr/share/man/man8/maglevd.8.gz` | Man page |
-| `/usr/share/man/man1/maglevc.1.gz` | Man page |
+## Running
 
 After installing, the unit is enabled but not started automatically:
 
 ```sh
-# edit /etc/maglev/maglev.yaml, then:
-systemctl start maglevd
+# edit /etc/vpp-maglev/maglev.yaml, then:
+systemctl enable --now vpp-maglevd
 ```
 
-## Run
+Or run the server and client by hand:
 
 ```sh
-maglevd --config /etc/maglev/maglev.yaml --grpc-addr :9090
+maglevd --config /etc/vpp-maglev/maglev.yaml --grpc-addr :9090
 maglevd --version                        # print version and exit
 
 maglevc --server localhost:9090          # interactive shell
-maglevc show backend nginx0-ams          # one-shot
+maglevc show frontends                   # one-shot
 maglevc -color=false show backends       # one-shot, no ANSI color
 maglevc set backend nginx0-ams pause
 ```
@@ -58,35 +41,7 @@ maglevc set backend nginx0-ams pause
 Send `SIGHUP` to `maglevd` to reload config without restarting.
 `maglevd` requires `CAP_NET_RAW` for ICMP health checks.
 
-## Minimal config
-
-```yaml
-maglev:
-  healthchecks:
-    http:
-      type: http
-      port: 80
-      params:
-        path: /healthz
-      interval: 2s
-      timeout: 3s
-
-  backends:
-    web0: {address: 192.0.2.10, healthcheck: http}
-    web1: {address: 192.0.2.11, healthcheck: http}
-
-  frontends:
-    web:
-      address: 192.0.2.1
-      protocol: tcp
-      port: 80
-      pools:
-        - name: primary
-          backends:
-            web0: {}
-            web1: {}
-```
-
+Check out a minimal configuration file in [[debian/maglev.yaml](debian/maglev.yaml)].
 See [docs/user-guide.md](docs/user-guide.md) for flags, signals, and `maglevc` usage.
 See [docs/config-guide.md](docs/config-guide.md) for the full configuration reference.
 See [docs/healthchecks.md](docs/healthchecks.md) for health state machine details.
@@ -95,5 +50,5 @@ See [docs/healthchecks.md](docs/healthchecks.md) for health state machine detail
 
 ```sh
 docker build -t maglevd .
-docker run --cap-add NET_RAW -v /etc/maglev:/etc/maglev maglevd
+docker run --cap-add NET_RAW -v /etc/vpp-maglev:/etc/vpp-maglev maglevd
 ```