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/mood/mood-form.tsx

@@ -22,7 +22,7 @@ import {
 } from "@/components/ui/dropdown-menu";
 import { Input } from "@/components/ui/input";
 import { Textarea } from "@/components/ui/textarea";
-import { DateTimeInput } from "@/components/ui/date-input";
+import { DateTimeField } from "@/components/ui/date-time-field";
 import { Label } from "@/components/ui/label";
 import {
   ListChecks,
@@ -511,10 +511,10 @@ export function MoodForm({ onSuccess, onCancel, footerSlot }: MoodFormProps) {
 
             <div className="space-y-2">
               <Label htmlFor="mood-logged-at">{t("mood.timestamp")}</Label>
-              <DateTimeInput
+              <DateTimeField
                 id="mood-logged-at"
                 value={moodLoggedAt}
-                onChange={(e) => setMoodLoggedAt(e.target.value)}
+                onChange={setMoodLoggedAt}
                 // v1.17 W1b — match the server bound: no future instant.
                 max={getDefaultMoodLoggedAtValue()}
                 required

src/components/mood/mood-list.tsx

@@ -29,7 +29,7 @@ import {
 } from "@/components/ui/dropdown-menu";
 import { Input } from "@/components/ui/input";
 import { Textarea } from "@/components/ui/textarea";
-import { DateTimeInput } from "@/components/ui/date-input";
+import { DateTimeField } from "@/components/ui/date-time-field";
 import { Label } from "@/components/ui/label";
 import {
   Table,
@@ -844,10 +844,10 @@ export function MoodList({ onAddFirst }: MoodListProps = {}) {
 
             <div className="space-y-2">
               <Label htmlFor="edit-mood-logged-at">{t("mood.timestamp")}</Label>
-              <DateTimeInput
+              <DateTimeField
                 id="edit-mood-logged-at"
                 value={editMoodLoggedAt}
-                onChange={(e) => setEditMoodLoggedAt(e.target.value)}
+                onChange={setEditMoodLoggedAt}
                 // v1.17 W1b — match the server bound: no future instant.
                 max={toDateTimeLocalValue(new Date().toISOString())}
                 required