feat(11-04): add the websockets health, VAPID key and test-push commands

- centrifugo.Client.Info probes the info API method; an error body fails
- websockets:health ports CentrifugoHealthCheck: exits 1 without an API
  key or when the probe fails, prints the Setting/Value table otherwise
- websockets:generate-vapid-keys prints a new P-256 pair, shows configured
  keys only truncated, and --update persists them to overrides.yaml
- websockets:test-push reads subscriptions from an app-published
  SubscriptionSource, refuses to send while push is disabled and sends
  one encrypted push per subscription
- no command prints a configured private key or the Centrifugo API key
- flare and lighthouse READMEs document the CLI commands

modules/lighthouse/centrifugo/commands.go

@@ -0,0 +1,69 @@
+package centrifugo
+
+import (
+	"context"
+	"errors"
+
+	"git.golem15.com/golem15/summercms/modules/backpack"
+	"git.golem15.com/golem15/summercms/modules/bonfire"
+)
+
+// HealthCommandName is the name of the Centrifugo health check command.
+const HealthCommandName = "websockets:health"
+
+// errHealthFailed is returned by the health command after it has printed
+// why the check failed, so the binary exits 1.
+var errHealthFailed = errors.New(HealthCommandName + ": check failed")
+
+// Commands returns the Centrifugo console commands for an application
+// binary: the HealthCommandName check. An application appends them to the
+// commands its plugin returns from Commands.
+func Commands(app *backpack.App) []bonfire.Command {
+	return []bonfire.Command{healthCommand(app)}
+}
+
+// healthCommand ports the WinterCMS CentrifugoHealthCheck command. The
+// WinterCMS command only read the local configuration; this one also calls
+// the Centrifugo info API, so a wrong URL or key fails the check. The API
+// key is never printed.
+func healthCommand(app *backpack.App) bonfire.Command {
+	return bonfire.Command{
+		Name:        HealthCommandName,
+		Description: "Check Centrifugo connection health",
+		Run: func(ctx context.Context, _ bonfire.Input, out bonfire.Output) error {
+			var cfg Config
+			if app != nil {
+				cfg = LoadConfig(app.Config)
+			} else {
+				cfg = LoadConfig(nil)
+			}
+			client := NewClient(cfg, nil)
+			if !client.Enabled() {
+				out.Error("Centrifugo not configured (API key missing)")
+				out.Println("Set SUMMER_REALTIME__CENTRIFUGO__API_KEY in the environment")
+				return errHealthFailed
+			}
+			out.Info("Checking Centrifugo connection...")
+			out.Println("API URL: " + cfg.APIURL)
+			if _, err := client.Info(ctx); err != nil {
+				out.Error("Connection check failed: " + err.Error())
+				return errHealthFailed
+			}
+			info := client.DebugInfo()
+			out.Success("Configuration OK")
+			out.Table([]string{"Setting", "Value"}, [][]string{
+				{"API URL", info.APIURL},
+				{"Enabled", yesNo(info.Enabled)},
+				{"API Key Set", yesNo(info.APIKeySet)},
+			})
+			return nil
+		},
+	}
+}
+
+func yesNo(b bool) string {
+	if b {
+		return "Yes"
+	}
+	return "No"
+}