libptouch を複数ソースに分割し src/lib に配置

- core / usb / print / status / png と libptouch_internal.h に分割
- 旧単一ファイル src/libptouch.c を削除
- CMake のソース一覧と include パスを更新
- README・libptouch.h の参照パスを追随

Made-with: Cursor

src/lib/libptouch_internal.h

@@ -0,0 +1,37 @@
+/*
+ * libptouch — internal declarations (not installed)
+ *
+ * Author: knb
+ * Email: knb@artif.org
+ */
+
+#ifndef LIBPTOUCH_INTERNAL_H
+#define LIBPTOUCH_INTERNAL_H
+
+#include "libptouch.h"
+
+#include <libusb.h>
+#include <stddef.h>
+
+struct libptouch_ctx {
+	libptouch_err_t last_code;
+	char last_msg[256];
+	int usb_open;
+	struct libusb_context *usb_ctx;
+	struct libusb_device_handle *usb_handle;
+	int claimed_interface; /* -1 if none */
+	uint8_t bulk_out_ep;
+	uint8_t bulk_in_ep;
+};
+
+void ptouch_set_error(libptouch_ctx *ctx, libptouch_err_t code, const char *msg);
+void ptouch_set_error_usb(libptouch_ctx *ctx, int libusb_err, const char *what);
+
+int ptouch_bulk_out(libusb_device_handle *h, uint8_t ep, const uint8_t *data,
+		    int len, unsigned int timeout_ms);
+int ptouch_bulk_in_exact(libusb_device_handle *h, uint8_t ep, uint8_t *buf,
+			 int len, unsigned int timeout_ms);
+libptouch_err_t ptouch_bulk_send_job(libptouch_ctx *ctx, const uint8_t *buf,
+				     size_t len, const char *what);
+
+#endif /* LIBPTOUCH_INTERNAL_H */