feat: refine BGP template handling and documentation updates. Remove local IP requirements in BGP template options, simplifying the configuration to focus on ASN. Update OpenAPI documentation to clarify BIRD parameters and enhance user guidance on JSON settings format in the UI. Adjust tests to align with the new BGP template structure.

internal/pipeline/refresh.go

@@ -285,8 +285,6 @@ func buildPreviewFragments(st store.Backend, tenantID, moduleID, revisionID stri
 
 	locals := birdLocalsFromStore(st, tenantID)
 	tplBody, err := birdfmt.RenderBGPTemplates(birdfmt.BGPTemplatesOptions{
-		LocalIPv4:      locals.localV4,
-		LocalIPv6:      locals.localV6,
 		LocalASN:       locals.localASN,
 		ExportFilterV4: birdFilterNameV4,
 		ExportFilterV6: birdFilterNameV6,
@@ -364,6 +362,8 @@ func birdLocalsFromStore(st store.Backend, tenantID string) birdLocals {
 	}
 	if s := stringFromSettingsMap(settings, "bird_bgp_source_ipv4"); s != "" {
 		loc.sourceV4 = s
+		// BIRD router id must be an IPv4 address; align with BGP source when operator sets it.
+		loc.routerID = strings.TrimSpace(s)
 	}
 	if s := stringFromSettingsMap(settings, "bird_bgp_source_ipv6"); s != "" {
 		loc.sourceV6 = s
@@ -445,7 +445,7 @@ func effectivePeerLocals(loc birdLocals, pol peerPolicyJSON) (v4, v6 string, asn
 	return v4, v6, asn
 }
 
-// peerNeedsLocalOverride is true when the peer's effective local IP or ASN differs from tenant defaults in the BGP template.
+// peerNeedsLocalOverride is true when the peer's effective local IP or ASN should override template "local as …" (add explicit "local <addr> as …" on the peer).
 func peerNeedsLocalOverride(loc birdLocals, effLocal string, effASN uint32, ipv4 bool) bool {
 	if ipv4 {
 		return strings.TrimSpace(effLocal) != strings.TrimSpace(loc.localV4) || effASN != loc.localASN