feat: New io module

- Add module for io
- Move common io parts to new module

modules/io/_io_module.scss

@@ -0,0 +1,65 @@
+header,
+aside,
+footer {
+	&.io {
+		nav li {
+			margin: 0;
+		}
+
+		nav > div:not(.spacer),
+		nav > span,
+		.a_button {
+			@extend %basic;
+			@extend %size_io_button;
+		}
+
+		.a_button {
+			color: $color_text_io;
+			background-color: $color_back_io;
+
+			&:active,
+			&:focus,
+			&:hover {
+				background-color: transparentize($color_highlight_basic, 0.8);
+			}
+		}
+	}
+}
+
+header,
+aside {
+	&.io {
+		padding: $space_basic;
+
+		input,
+		button,
+		textarea,
+		select {
+			margin-inline: $space_half;
+		}
+
+		input {
+			@extend .input_io;
+		}
+
+		textarea {
+			@extend .io_textarea;
+		}
+
+		select {
+			@extend .io_select;
+		}
+
+		button {
+			@extend .button_io;
+		}
+	}
+}
+
+header,
+footer {
+	&.io {
+		@extend %flex-inline;
+		align-items: stretch;
+	}
+}