feat(docs): update speaker installation instructions and logging details

- Enhanced the speaker installation documentation to clarify the use of TCP port 179 and the logging commands for monitoring BIRD and evobgp-agent.
- Updated the speaker form dialog to include additional information about MikroTik connections and logging commands.
- Modified the BIRD configuration to include logging to stderr for better visibility during operations.
- Adjusted the Docker Compose configuration to ensure proper network settings and sysctl configurations for BGP functionality.

internal/pipeline/speaker_overlay.go

@@ -19,9 +19,13 @@ func BirdLocalsForSpeaker(st store.Backend, tenantID, speakerID string) birdLoca
 		return loc
 	}
 	meta := store.ParseSpeakerMeta(sp.MetaJSON)
-	if s := strings.TrimSpace(meta.BirdBgpSourceIPv4); s != "" {
-		loc.routerID = s
-		loc.localV4 = s
+	src := strings.TrimSpace(meta.BirdBgpSourceIPv4)
+	if src == "" {
+		src = strings.TrimSpace(meta.NodeIPv4)
+	}
+	if src != "" {
+		loc.routerID = src
+		loc.localV4 = src
 	}
 	if s := strings.TrimSpace(meta.BirdBgpSourceIPv6); s != "" {
 		loc.localV6 = s
@@ -32,7 +36,7 @@ func BirdLocalsForSpeaker(st store.Backend, tenantID, speakerID string) birdLoca
 // OverlayFragmentsForSpeaker re-renders bird.conf and peers fragment with speaker-specific BIRD locals.
 func OverlayFragmentsForSpeaker(st store.Backend, tenantID, speakerID, revisionID string, frags map[string]string) (map[string]string, error) {
 	if frags == nil {
-		return nil, fmt.Errorf("pipeline: overlay: nil fragments")
+		frags = map[string]string{}
 	}
 	locals := BirdLocalsForSpeaker(st, tenantID, speakerID)
 	out := make(map[string]string, len(frags))