Pools, CLI, versioning, Debian packaging, HTTPS fix

- Replaced flat `backends: [...]` list on frontends with an ordered `pools:`
  list; each pool has a name and a map of backends with per-pool weights (0–100,
  default 100). Pools express priority: first pool with a healthy backend wins.
- Removed global backend weight (was on the backend, now lives in the pool).
- Config validation enforces non-empty pools, non-empty pool names, weight
  range, and consistent address families across all pools of a frontend.

- Added `PoolBackendInfo { name, weight }` and changed `PoolInfo.backends` from
  `repeated string` to `repeated PoolBackendInfo` so weights are visible over
  the API.

- Full interactive shell with readline, tab completion, and `?` inline help.
- Command tree parser (Walk) handles fixed keywords and dynamic slot nodes;
  prefix matching with exact-match priority.
- Commands: `show version/frontends/frontend/backends/backend/healthchecks/
  healthcheck`, `set backend <name> pause|resume`, `quit`/`exit`.
- `show frontend` output is hierarchical (pools → backends) with per-backend
  weights and `[disabled]` notation; pool section uses fixed-width formatting
  so ANSI color codes don't corrupt tabwriter alignment.
- `-color` flag (default true) wraps static field labels in dark-blue ANSI;
  works correctly with tabwriter because all labels carry identical-length
  escape sequences.

- `cmd/version.go` package holds `version`, `commit`, `date` vars set at build
  time via `-ldflags -X`.
- `make build` / `make build-amd64` / `make build-arm64` all inject
  `VERSION=0.1.1`, `COMMIT_HASH` (from `git rev-parse --short HEAD`), and
  `DATE` (UTC ISO-8601).
- `maglevc` prints version on interactive startup and exposes `show version`.
- `maglevd` logs version/commit/date at startup; `-version` flag prints and exits.

- `doHTTPProbe` was building a `https://` target URL even though TLS was already
  applied to the connection inside `inNetns`. `http.Transport` then wrapped the
  connection in a second TLS layer, producing "http: server gave HTTP response
  to HTTPS client". Fixed by always using `http://` in the target URL.
- Added `TestHTTPSProbe` using `httptest.NewTLSServer` to cover the full path.

- New `docs/user-guide.md`: maglevd flags/signals, maglevc commands, shell
  completion, and command-tree parser walkthrough.
- New `docs/healthchecks.md`: state machine, rise/fall model, probe intervals,
  all transition events with log examples.
- Updated `docs/config-guide.md`: pools design, removed global weight from
  backends, updated all examples.
- Updated `README.md`: packaging table, build paths, corrected binary locations
  (`/usr/sbin/maglevd`), config filename (`.yaml`).

- `debian/` directory contains `control.in`, `maglevd.service`, `default.maglev`,
  `maglev.yaml` (example config), `conffiles`, `postinst`, `prerm`.
- `debian/build-deb.sh` stages a package tree and calls `dpkg-deb`; emits
  `build/vpp-maglev_<version>~<commit>_<arch>.deb`.
- Cross-compiles for amd64 and arm64 in one `make pkg-deb` invocation.
- `maglevd` installed to `/usr/sbin/`, `maglevc` to `/usr/bin/`.
- Service reads `MAGLEV_CONFIG` from `/etc/default/maglev`
  (default: `/etc/maglev/maglev.yaml`).
- Man pages `maglevd(8)` and `maglevc(1)` live in `docs/` and are gzip'd into
  the package.
- All build output goes to `build/<arch>/`; `build/` is gitignored.

internal/grpcapi/server.go

@@ -137,13 +137,24 @@ func (s *Server) WatchBackendEvents(_ *WatchRequest, stream Maglev_WatchBackendE
 // ---- conversion helpers ----------------------------------------------------
 
 func frontendToProto(name string, fe config.Frontend) *FrontendInfo {
+	pools := make([]*PoolInfo, 0, len(fe.Pools))
+	for _, p := range fe.Pools {
+		pi := &PoolInfo{Name: p.Name}
+		for bName, pb := range p.Backends {
+			pi.Backends = append(pi.Backends, &PoolBackendInfo{
+				Name:   bName,
+				Weight: int32(pb.Weight),
+			})
+		}
+		pools = append(pools, pi)
+	}
 	return &FrontendInfo{
-		Name:         name,
-		Address:      fe.Address.String(),
-		Protocol:     fe.Protocol,
-		Port:         uint32(fe.Port),
-		Description:  fe.Description,
-		BackendNames: fe.Backends,
+		Name:        name,
+		Address:     fe.Address.String(),
+		Protocol:    fe.Protocol,
+		Port:        uint32(fe.Port),
+		Description: fe.Description,
+		Pools:       pools,
 	}
 }
 
@@ -153,7 +164,6 @@ func backendToProto(snap checker.BackendSnapshot) *BackendInfo {
 		Address:     snap.Health.Address.String(),
 		State:       snap.Health.State.String(),
 		Enabled:     snap.Config.Enabled,
-		Weight:      int32(snap.Config.Weight),
 		Healthcheck: snap.Config.HealthCheck,
 	}
 	for _, t := range snap.Health.Transitions {