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/config.go

@@ -5,10 +5,27 @@ import (
 	"os"
 	"path/filepath"
 	"strconv"
+	"strings"
 
 	"fiatjaf.com/nostr"
 )
 
+// parseChannels splits a comma-separated channel list into cleaned group ids: a
+// leading `#` is tolerated and blanks/dupes are dropped. Order is preserved.
+func parseChannels(s string) []string {
+	var out []string
+	seen := map[string]bool{}
+	for _, part := range strings.Split(s, ",") {
+		id := strings.TrimPrefix(strings.TrimSpace(part), "#")
+		if id == "" || seen[id] {
+			continue
+		}
+		seen[id] = true
+		out = append(out, id)
+	}
+	return out
+}
+
 func envOr(key, fallback string) string {
 	if v := os.Getenv(key); v != "" {
 		return v