feat: add LSPS7 UniFFI bindings and generated Swift/Kotlin bindings

Add LSPS7 types (LSPS7OrderResponse, LSPS7ExtendableChannel,
LSPS7OriginalOrder, LSPS7OrderState, LSPS7OrderId) to UDL, FFI type
converters, and ArcedNodeBuilder for UniFFI support.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: kaloudis

bindings/ldk_node.udl

@@ -103,6 +103,7 @@ interface Builder {
 	void set_pathfinding_scores_source(string url);
 	void set_liquidity_source_lsps1(PublicKey node_id, SocketAddress address, string? token);
 	void set_liquidity_source_lsps2(PublicKey node_id, SocketAddress address, string? token);
+	void set_liquidity_source_lsps7(PublicKey node_id, SocketAddress address, string? token);
 	void set_storage_dir_path(string storage_dir_path);
 	void set_filesystem_logger(string? log_file_path, LogLevel? max_log_level);
 	void set_log_facade_logger();
@@ -151,6 +152,7 @@ interface Node {
 	OnchainPayment onchain_payment();
 	UnifiedQrPayment unified_qr_payment();
 	LSPS1Liquidity lsps1_liquidity();
+	LSPS7Liquidity lsps7_liquidity();
 	[Throws=NodeError]
 	void connect(PublicKey node_id, SocketAddress address, boolean persist);
 	[Throws=NodeError]
@@ -289,6 +291,15 @@ interface LSPS1Liquidity {
 	LSPS1OrderStatus check_order_status(LSPS1OrderId order_id);
 };
 
+interface LSPS7Liquidity {
+	[Throws=NodeError]
+	sequence<LSPS7ExtendableChannel> get_extendable_channels();
+	[Throws=NodeError]
+	LSPS7OrderResponse create_order(string short_channel_id, u32 channel_extension_expiry_blocks, string? token, string? refund_onchain_address);
+	[Throws=NodeError]
+	LSPS7OrderResponse check_order_status(string order_id);
+};
+
 [Error]
 enum NodeError {
 	"AlreadyRunning",
@@ -559,6 +570,34 @@ enum LSPS1PaymentState {
 	"Refunded",
 };
 
+dictionary LSPS7OrderResponse {
+	LSPS7OrderId order_id;
+	LSPS7OrderState order_state;
+	u32 channel_extension_expiry_blocks;
+	u32 new_channel_expiry_block;
+	LSPS1PaymentInfo payment;
+	LSPS7ExtendableChannel channel;
+};
+
+dictionary LSPS7ExtendableChannel {
+	LSPS7OriginalOrder? original_order;
+	sequence<string>? extension_order_ids;
+	string short_channel_id;
+	u32 max_channel_extension_expiry_blocks;
+	u32 expiration_block;
+};
+
+dictionary LSPS7OriginalOrder {
+	string id;
+	string service;
+};
+
+enum LSPS7OrderState {
+	"Created",
+	"Completed",
+	"Failed",
+};
+
 [NonExhaustive]
 enum Network {
 	"Bitcoin",
@@ -901,6 +940,9 @@ typedef string NodeAlias;
 [Custom]
 typedef string LSPS1OrderId;
 
+[Custom]
+typedef string LSPS7OrderId;
+
 [Custom]
 typedef string LSPSDateTime;