seed default channel(s) on boot

fresh relay seeds configured open channels (RELAY_DEFAULT_CHANNELS,
default general) so a client always has a room. relay-signed 9007
through the normal pipeline; idempotent; never reopens a closed group.

also adds mission/roadmap and separation rationale to the readme.

cmd/nostermd/main.go

@@ -10,6 +10,7 @@
 package main
 
 import (
+	"context"
 	"log"
 	"net/http"
 	"os"
@@ -63,8 +64,10 @@ func main() {
 		contact: envOr("RELAY_CONTACT", "relay@nosterm.com"),
 		// Optional message-of-the-day shown in the client's relay server window;
 		// defaults to the nerdworks.io banner when unset.
-		motd:   envOr("RELAY_MOTD", defaultMOTD),
-		fedCfg: fedCfg,
+		motd: envOr("RELAY_MOTD", defaultMOTD),
+		// Seed at least one open channel so a fresh relay is never empty.
+		defaultChannels: parseChannels(envOr("RELAY_DEFAULT_CHANNELS", "general")),
+		fedCfg:          fedCfg,
 	})
 
 	// Reconstruct membership/metadata from persisted events so groups survive
@@ -73,6 +76,10 @@ func main() {
 		log.Printf("replayed %d group management event(s) from storage", replayed)
 	}
 
+	// Seed default channel(s) after replay so a fresh relay always has a room to
+	// join; existing channels are left untouched.
+	app.SeedDefaultChannels(context.Background())
+
 	// Retention: prune old chat messages so the store doesn't grow forever.
 	stopRetention := retention.Start(store, retention.Config{
 		MaxAge:      time.Duration(envIntOr("RELAY_RETENTION_DAYS", 0)) * 24 * time.Hour,