fix: prevent date picker from selecting past times at hour breakpoints (#1814)

The function previously used <= for hour comparisons, which caused it to
return a breakpoint hour even if the current time had passed it. For example,
at 15:54, it would return 15 (3:00 PM), which is in the past.

Now the function checks both hours and minutes:
- If current time is before a breakpoint hour, return that hour
- If current time is exactly at a breakpoint hour with 0 minutes, return that hour
- If current time is past a breakpoint (hour with minutes > 0), return the next breakpoint

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: kolaente <13721712+kolaente@users.noreply.github.com>

frontend/src/helpers/time/calculateNearestHours.ts

@@ -1,24 +1,33 @@
 export function calculateNearestHours(currentDate: Date = new Date()): number {
-	if (currentDate.getHours() <= 9 || currentDate.getHours() > 21) {
+	const hours = currentDate.getHours()
+	const minutes = currentDate.getMinutes()
+	
+	// Helper to check if current time is before a given hour breakpoint
+	// Returns true if we're before the hour, or at the hour with 0 minutes
+	const isBeforeOrAt = (breakpoint: number): boolean => {
+		return hours < breakpoint || (hours === breakpoint && minutes === 0)
+	}
+	
+	if (isBeforeOrAt(9) || hours > 21) {
 		return 9
 	}
 
-	if (currentDate.getHours() <= 12) {
+	if (isBeforeOrAt(12)) {
 		return 12
 	}
 
-	if (currentDate.getHours() <= 15) {
+	if (isBeforeOrAt(15)) {
 		return 15
 	}
 
-	if (currentDate.getHours() <= 18) {
+	if (isBeforeOrAt(18)) {
 		return 18
 	}
 
-	if (currentDate.getHours() <= 21) {
+	if (isBeforeOrAt(21)) {
 		return 21
 	}
 	
-	// Same case as in the first if, will never be called
+	// After 21:00 with minutes > 0, return 9 for next day
 	return 9
 }

frontend/src/helpers/time/calculateNearestTime.test.ts

@@ -90,3 +90,39 @@ test('22:40', () => {
 	date.setMinutes(0)
 	expect(calculateNearestHours(date)).toBe(9)
 })
+
+// Test cases for the bug: when current time is past a breakpoint hour
+test('12:30 should return next breakpoint (15), not current (12)', () => {
+	const date = new Date()
+	date.setHours(12)
+	date.setMinutes(30)
+	expect(calculateNearestHours(date)).toBe(15)
+})
+
+test('15:54 should return next breakpoint (18), not current (15)', () => {
+	const date = new Date()
+	date.setHours(15)
+	date.setMinutes(54)
+	expect(calculateNearestHours(date)).toBe(18)
+})
+
+test('18:45 should return next breakpoint (21), not current (18)', () => {
+	const date = new Date()
+	date.setHours(18)
+	date.setMinutes(45)
+	expect(calculateNearestHours(date)).toBe(21)
+})
+
+test('21:30 should return next day breakpoint (9), not current (21)', () => {
+	const date = new Date()
+	date.setHours(21)
+	date.setMinutes(30)
+	expect(calculateNearestHours(date)).toBe(9)
+})
+
+test('9:01 should return next breakpoint (12), not current (9)', () => {
+	const date = new Date()
+	date.setHours(9)
+	date.setMinutes(1)
+	expect(calculateNearestHours(date)).toBe(12)
+})