cubelinux: the release starts with a digit, because module tooling demands it

The store's sort no longer lives on the kernel stack (heapsort, see the parent
commit's gate), and the release is now 6.19.3-cubelinux0.6 instead of
CUBELinux.0.6 — depmod/mkinitramfs reject a version whose first character is
not numeric, so the literal name cannot be uname -r. The box's own kernel uses
the same shape (6.19.3-cube+); this is the same concession.

include/uapi/linux/cube.h

@@ -40,5 +40,29 @@ struct cube_args {
 #define CUBE_OP_GET	2	/* read them back */
 #define CUBE_OP_DEL	3	/* remove the record */
 #define CUBE_OP_SYNC	4	/* fold the log into the image */
+#define CUBE_OP_ENUM	5	/* walk the records of a space, in batches */
+#define CUBE_OP_SPACES	6	/* walk the spaces that hold records */
+
+/*
+ * The walk's argument block: its own block rather than a wider `cube_args`, because it needs a
+ * cursor and a buffer, and the coordinate would otherwise be both an input and an output.
+ *
+ * Records are packed as `key(24) | value_len(u32, little-endian) | value`, in the store's own
+ * order — space first, then key — which is the order a checkpoint writes them and the order the
+ * userspace store returns them, so a kernel listing and a userspace listing can be compared
+ * directly. The space is not repeated per record: the caller named it.
+ */
+struct cube_enum_args {
+	__u32 size;		/* sizeof(struct cube_enum_args) as the caller built it */
+	__u32 op;		/* CUBE_OP_ENUM or CUBE_OP_SPACES */
+	__u8 space[32];		/* in: the space to walk; out: the space found (CUBE_OP_SPACES) */
+	__u64 cursor;		/* in: 0 to start, or what the last call returned;
+				 * out: what to pass next
+				 */
+	__u64 value;		/* user pointer: where to put the records */
+	__u64 len;		/* in: the buffer's capacity;
+				 * out: bytes written, or on -ERANGE what would be needed
+				 */
+};
 
 #endif /* _UAPI_LINUX_CUBE_H */