[management] Clean up after account deletion (#7812)

Deleting an account left state behind that DeleteAccount's store
associations don't reach. The Agent Network tables outlived the account,
keeping its gateway domain claimed and its provider API keys stored. The
proxies kept serving its gateway until they next resynced. Cloud-side
state, such as managed proxy deployments, had no way to be cleaned up at
all.

Account deletion now runs registered hooks after the permission check
and before any users or data are removed. A failing hook aborts the
deletion. Agent Network registers one that tells the proxies to drop the
account's gateway mappings. The account's settings, providers, policies,
guardrails and budget rules are deleted in the account's transaction.
Consumption counters, and the access logs of deleted accounts, are left
to the background cleanup; usage records are kept.

e2e/harness/proxy.go

@@ -3,13 +3,17 @@
 package harness
 
 import (
+	"bytes"
 	"context"
+	"encoding/json"
 	"fmt"
+	"io"
 	"os"
 	"time"
 
 	"github.com/docker/docker/api/types/container"
 	"github.com/testcontainers/testcontainers-go"
+	tcexec "github.com/testcontainers/testcontainers-go/exec"
 	"github.com/testcontainers/testcontainers-go/wait"
 )
 
@@ -114,6 +118,41 @@ func StartProxy(ctx context.Context, c *Combined, proxyToken string, envOverride
 	return &Proxy{container: ctr, workDir: workDir}, nil
 }
 
+// ProxyDebugClient is one per-account embedded client the proxy runs, as the
+// proxy's debug endpoint reports it.
+type ProxyDebugClient struct {
+	AccountID    string   `json:"account_id"`
+	ServiceCount int      `json:"service_count"`
+	ServiceKeys  []string `json:"service_keys"`
+}
+
+// DebugClients lists the per-account clients the proxy is running, through
+// the proxy's own debug CLI inside the container. The proxy must be started
+// with NB_PROXY_DEBUG_ENDPOINT=true.
+func (p *Proxy) DebugClients(ctx context.Context) ([]ProxyDebugClient, error) {
+	code, reader, err := p.container.Exec(ctx,
+		[]string{"/usr/bin/netbird-proxy", "debug", "clients", "--json"}, tcexec.Multiplexed())
+	if err != nil {
+		return nil, fmt.Errorf("exec debug clients: %w", err)
+	}
+	out, _ := io.ReadAll(reader)
+	if code != 0 {
+		return nil, fmt.Errorf("debug clients exited %d: %s", code, string(out))
+	}
+	// stderr is multiplexed in; the JSON document starts at the first brace.
+	start := bytes.IndexByte(out, '{')
+	if start < 0 {
+		return nil, fmt.Errorf("no JSON in debug clients output: %s", string(out))
+	}
+	var resp struct {
+		Clients []ProxyDebugClient `json:"clients"`
+	}
+	if err := json.NewDecoder(bytes.NewReader(out[start:])).Decode(&resp); err != nil {
+		return nil, fmt.Errorf("decode debug clients output: %w", err)
+	}
+	return resp.Clients, nil
+}
+
 // Logs returns the proxy container logs, for diagnostics on failure.
 func (p *Proxy) Logs(ctx context.Context) string {
 	return containerLogs(ctx, p.container)