fix: deduplicate chart axis labels using tickFormatter map

Co-authored-by: aider (gemini/gemini-3.1-pro-preview) <aider@aider.chat>

client/src/App.js

@@ -84,7 +84,27 @@ function useSensor(measurement, name, end, duration) {
 	};
 
 	const isDST = end.tz('America/Edmonton').isDST();
-	const tickFormatter = (timeStr) => memoConvertTZ(isDST, timeStr, duration.format);
+
+	const labelMap = {};
+	if (Array.isArray(data)) {
+		let lastLabel = null;
+		data.forEach(d => {
+			const lbl = memoConvertTZ(isDST, d.time, duration.format);
+			if (lbl !== lastLabel) {
+				labelMap[d.time] = lbl;
+				lastLabel = lbl;
+			} else {
+				labelMap[d.time] = '';
+			}
+		});
+	}
+
+	const tickFormatter = (timeStr) => {
+		if (labelMap[timeStr] !== undefined) {
+			return labelMap[timeStr];
+		}
+		return memoConvertTZ(isDST, timeStr, duration.format);
+	};
 
 	return [data, loading, tickFormatter];
 };
@@ -712,7 +732,27 @@ function MultiLineChart({title, measurement, dataKey, sensors, colors, end, dura
 	};
 
 	const isDST = end.tz('America/Edmonton').isDST();
-	const tickFormatter = (timeStr) => memoConvertTZ(isDST, timeStr, duration.format);
+
+	const labelMap = {};
+	if (Array.isArray(data)) {
+		let lastLabel = null;
+		data.forEach(d => {
+			const lbl = memoConvertTZ(isDST, d.time, duration.format);
+			if (lbl !== lastLabel) {
+				labelMap[d.time] = lbl;
+				lastLabel = lbl;
+			} else {
+				labelMap[d.time] = '';
+			}
+		});
+	}
+
+	const tickFormatter = (timeStr) => {
+		if (labelMap[timeStr] !== undefined) {
+			return labelMap[timeStr];
+		}
+		return memoConvertTZ(isDST, timeStr, duration.format);
+	};
 
 	return (
 		<ChartContainer