feat(ui): use material-icons

`material-symbols-outlined` was specifically used.

src/components/CalculatorContainer/CorrectionButton.vue

@@ -13,21 +13,28 @@ interface CustomEvents {
 	(event: "clearEntryScreen"): void
 }
 const emit = defineEmits<CustomEvents>()
-const mayOneDigitOnly = computed(() => props.value === "")
+const mayClearOneDigitOnly = computed(() => props.value === "")
 const mayClearEntryScreenOnly = computed(() => props.value === "CE")
 
 function clearScreens() {
 	if (mayClearEntryScreenOnly.value) emit("clearEntryScreen")
-	if (mayOneDigitOnly.value) emit("clearOneDigit")
+	if (mayClearOneDigitOnly.value) emit("clearOneDigit")
 	else emit("clearAllScreens")
 }
 </script>
 
 <template>
 	<button class="correction-button" @click="clearScreens">
-		{{ props.value }}
+		<span v-if="mayClearOneDigitOnly" class="material-symbols-outlined one-digit">
+			backspace
+		</span>
+		<span v-else>
+			{{ props.value }}
+		</span>
 	</button>
 </template>
 
+
 <style scoped lang="scss">
+	@import "https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@48,400,0,0";
 </style>