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, 8 insertions, 4 deletions

diff --git a/src/lib/server/services/routines.ts b/src/lib/server/services/routines.ts
index ec03c50..a29872a 100644
--- a/src/lib/server/services/routines.ts
+++ b/src/lib/server/services/routines.ts
@@ -36,7 +36,9 @@ export async function add(
 			projectId,
 			name,
 			frequencyDays,
-			createdAt: new Date().toISOString(),
+			createdAt: Temporal.Now.instant().toString({
+				smallestUnit: 'millisecond',
+			}),
 		})
 		.returning();
 	return inserted;
@@ -91,7 +93,9 @@ export async function archive(id: number, db = defaultDb): Promise<void> {
 		...current,
 		version: current.version + 1,
 		archived: true,
-		archivedAt: new Date().toISOString(),
+		archivedAt: Temporal.Now.instant().toString({
+			smallestUnit: 'millisecond',
+		}),
 	});
 }
 
@@ -206,7 +210,7 @@ export interface ProjectDashboard {
 
 export async function loadProjectDashboard(
 	projectId: number,
-	now: number,
+	now: Temporal.Instant,
 	db = defaultDb,
 ): Promise<ProjectDashboard> {
 	const versions = await db
@@ -249,7 +253,7 @@ export interface ProjectsOverview {
 }
 
 export async function loadOverview(
-	now: number,
+	now: Temporal.Instant,
 	db = defaultDb,
 ): Promise<ProjectsOverview> {
 	const activeProjects = await db