feat(date): add DateTimeField and migrate datetime inputs

Add a dependency-free DateTimeField that paints the date part in the
user's date-order preference and the time part in the hour-cycle
preference over a hidden native datetime-local input, preserving the
local yyyy-MM-ddTHH:mm value contract. Migrate the seven DateTimeInput
callsites (measurement add/edit, mood add/edit, lab add/edit,
medication intake quick-add) so the chosen format is honoured there too,
and cover the field's value contract and per-preference rendering with a
component test.

src/components/labs/lab-form.tsx

@@ -7,7 +7,7 @@ import { Loader2 } from "lucide-react";
 import { toast } from "sonner";
 
 import { Button } from "@/components/ui/button";
-import { DateTimeInput } from "@/components/ui/date-input";
+import { DateTimeField } from "@/components/ui/date-time-field";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
 import { ResponsiveSheet } from "@/components/ui/responsive-sheet";
@@ -310,10 +310,10 @@ export function LabForm({
           </div>
           <div className="space-y-1.5">
             <Label htmlFor="lab-takenAt">{t("labs.form.takenAt")}</Label>
-            <DateTimeInput
+            <DateTimeField
               id="lab-takenAt"
               value={takenAt}
-              onChange={(e) => setTakenAt(e.target.value)}
+              onChange={setTakenAt}
               max={defaultTakenAtValue()}
               required
             />

src/components/labs/lab-history-list.tsx

@@ -7,7 +7,7 @@ import { toast } from "sonner";
 
 import { DeleteButton } from "@/components/data-list";
 import { Button } from "@/components/ui/button";
-import { DateTimeInput } from "@/components/ui/date-input";
+import { DateTimeField } from "@/components/ui/date-time-field";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
 import { ResponsiveSheet } from "@/components/ui/responsive-sheet";
@@ -285,10 +285,10 @@ export function LabHistoryList({ readings }: { readings: LabResultDto[] }) {
             </div>
             <div className="space-y-1.5">
               <Label htmlFor="lab-edit-takenAt">{t("labs.form.takenAt")}</Label>
-              <DateTimeInput
+              <DateTimeField
                 id="lab-edit-takenAt"
                 value={editTakenAt}
-                onChange={(e) => setEditTakenAt(e.target.value)}
+                onChange={setEditTakenAt}
                 required
               />
             </div>