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.

2 files changed, 4 insertions, 8 deletions

diff --git a/src/routes/projects/[id]/+page.server.ts b/src/routes/projects/[id]/+page.server.ts
index 7cb90ff..19aea9b 100644
--- a/src/routes/projects/[id]/+page.server.ts
+++ b/src/routes/projects/[id]/+page.server.ts
@@ -26,7 +26,7 @@ export const load: PageServerLoad = async ({ params }) => {
 	if (!project || project.archived) {
 		throw error(404, 'Projet introuvable');
 	}
-	const dashboard = await loadProjectDashboard(id, Date.now());
+	const dashboard = await loadProjectDashboard(id, Temporal.Now.instant());
 	const archived = await loadArchived(id);
 	return {
 		project: { id: project.id, name: project.name },
diff --git a/src/routes/projects/[id]/+page.svelte b/src/routes/projects/[id]/+page.svelte
index a58aeba..9931f40 100644
--- a/src/routes/projects/[id]/+page.svelte
+++ b/src/routes/projects/[id]/+page.svelte
@@ -9,6 +9,7 @@
 		parseIntervalToDays,
 		type RoutineState,
 	} from '$lib/shared/routine-metrics';
+	import { formatDayMonth } from '$lib/shared/temporal';
 
 	let { data, form } = $props();
 
@@ -30,11 +31,6 @@
 			: matchItems(data.archived, archiveFilter).map((m) => m.obj),
 	);
 
-	const dateFormatter = new Intl.DateTimeFormat('fr-FR', {
-		day: 'numeric',
-		month: 'short',
-	});
-
 	function sorted(routines: RoutineState[]): RoutineState[] {
 		return [...routines].sort(
 			(a, b) => b.overdueRatio - a.overdueRatio || a.name.localeCompare(b.name),
@@ -182,7 +178,7 @@
 						<span class="routine-meta">
 							{formatFrequency(routine.frequencyDays)}
 							{#if routine.lastDoneAt}
-								· fait le {dateFormatter.format(new Date(routine.lastDoneAt))}
+								· fait le {formatDayMonth(routine.lastDoneAt)}
 							{:else}
 								· jamais fait
 							{/if}
@@ -244,7 +240,7 @@
 							>
 							<span class="archived-date">
 								{formatFrequency(routine.frequencyDays)} · archivée le
-								{dateFormatter.format(new Date(routine.archivedAt))}
+								{formatDayMonth(routine.archivedAt)}
 							</span>
 						</li>
 					{/each}