Migrate date handling from Date to Temporal API

Routine scheduling, health series, service stamps, session expiry, and
date formatting move to native Temporal (Instant / ZonedDateTime in
UTC), with ISO strings kept at DB and chart boundaries. Ambient types
in src/temporal-ambient.d.ts cover the native runtime; no polyfill.
Observable behavior and stored formats are unchanged.

1 files changed, 11 insertions, 17 deletions

diff --git a/src/routes/projects/[projectId]/routine/[routineId]/+page.svelte b/src/routes/projects/[projectId]/routine/[routineId]/+page.svelte
index ab2644d..e593ad1 100644
--- a/src/routes/projects/[projectId]/routine/[routineId]/+page.svelte
+++ b/src/routes/projects/[projectId]/routine/[routineId]/+page.svelte
@@ -8,6 +8,7 @@
 		parseIntervalToDays,
 		computeHealthSeries,
 	} from '$lib/shared/routine-metrics';
+	import { formatDayMonth, formatDayMonthYear } from '$lib/shared/temporal';
 	let { data, form } = $props();
 	let name = $state('');
 	let frequency = $state('');
@@ -27,24 +28,19 @@
 		}
 	});
 	const frequencyDays = $derived(parseIntervalToDays(frequency));
-	const dateFormatter = new Intl.DateTimeFormat('fr-FR', {
-		day: 'numeric',
-		month: 'short',
-	});
-	const dateTimeFormatter = new Intl.DateTimeFormat('fr-FR', {
-		day: 'numeric',
-		month: 'short',
-		year: 'numeric',
-	});
 	const frozenAt = $derived(
 		data.routine.archived
-			? Date.parse(data.routine.archivedAt ?? data.routine.createdAt)
-			: Date.now(),
+			? Temporal.Instant.from(data.routine.archivedAt ?? data.routine.createdAt)
+			: Temporal.Now.instant(),
 	);
 	const series = $derived(
 		computeHealthSeries(data.routine, data.completions, frozenAt),
 	);
-	const markers = $derived(data.completions.map((c) => Date.parse(c.doneAt)));
+	const markers = $derived(
+		data.completions.map(
+			(c) => Temporal.Instant.from(c.doneAt).epochMilliseconds,
+		),
+	);
 </script>
 
 <main>
@@ -60,9 +56,7 @@
 	{#if data.routine.archived}
 		<p class="archived-badge">
 			Archivée le
-			{dateTimeFormatter.format(
-				new Date(data.routine.archivedAt ?? data.routine.createdAt),
-			)}
+			{formatDayMonthYear(data.routine.archivedAt ?? data.routine.createdAt)}
 		</p>
 	{/if}
 
@@ -144,7 +138,7 @@
 				<span class="chart-meta">
 					{formatFrequency(data.routine.frequencyDays)}
 					{#if data.state.lastDoneAt}
-						· fait le {dateFormatter.format(new Date(data.state.lastDoneAt))}
+						· fait le {formatDayMonth(data.state.lastDoneAt)}
 					{:else}
 						· jamais fait
 					{/if}
@@ -182,7 +176,7 @@
 		{#each data.completions as c (c.id)}
 			<li class="item-row item-row--card completion-row">
 				<span class="completion-date">
-					{dateTimeFormatter.format(new Date(c.doneAt))}
+					{formatDayMonthYear(c.doneAt)}
 				</span>
 				{#if c.note}
 					<span class="completion-note">{c.note}</span>