feat(amneziawg): support persistent keepalive ranges (#6881)

AmneziaWG clients accept a randomised PersistentKeepalive range such as 15-25,
which makes keepalive timing harder to fingerprint; the panel only stored a
single number. A client's keepalive may now be a range, validated the way
AmneziaWG parses it. The downloadable .conf and vpn:// profile carry the range,
Clash/Mihomo output gets its lower bound, and plain WireGuard stays scalar-only.
The range lives in an additive wg_keep_alive_range column, so the integer
column and an older panel binary keep working after a rollback.

tools/openapigen/walker.go

@@ -13,6 +13,7 @@ import (
 type walkOverride struct {
 	Field string
 	Kind  TypeKind
+	Type  TypeRef
 }
 
 type packageRequest struct {
@@ -122,7 +123,11 @@ func buildFields(fld *ast.Field, overrides []walkOverride) []Field {
 		t := exprToType(fld.Type)
 		for _, o := range overrides {
 			if o.Field == n.Name || o.Field == jsonName {
-				t = TypeRef{Kind: o.Kind}
+				if o.Type.Kind != "" {
+					t = o.Type
+				} else {
+					t = TypeRef{Kind: o.Kind}
+				}
 				break
 			}
 		}
@@ -145,7 +150,11 @@ func buildFields(fld *ast.Field, overrides []walkOverride) []Field {
 		t := exprToType(fld.Type)
 		for _, o := range overrides {
 			if o.Field == exprIdentName(fld.Type) || o.Field == jsonName {
-				t = TypeRef{Kind: o.Kind}
+				if o.Type.Kind != "" {
+					t = o.Type
+				} else {
+					t = TypeRef{Kind: o.Kind}
+				}
 				break
 			}
 		}