feat: Développer le composant Datepicker (#52)

| Numéro du ticket | Titre du ticket |
|------------------|-----------------|
|                  |                 |

## Description de la PR

## Modification du .env

## Check list

- [ ] Pas de régression
- [ ] TU/TI/TF rédigée
- [ ] TU/TI/TF OK
- [ ] CHANGELOG modifié

Co-authored-by: matthieu <matthieu@yuno.malio.fr>
Co-authored-by: THOLOT DECHENE Matthieu <matthieu@yuno.malio.fr>
Reviewed-on: #52
Co-authored-by: tristan <tristan@yuno.malio.fr>
Co-committed-by: tristan <tristan@yuno.malio.fr>

app/components/malio/date/composables/datetimeFormat.test.ts

@@ -0,0 +1,61 @@
+import {describe, expect, it} from 'vitest'
+import {
+  composeDateTime,
+  formatIsoDateTimeToDisplay,
+  isValidIsoDateTime,
+  splitDateTime,
+} from './datetimeFormat'
+
+describe('datetimeFormat', () => {
+  describe('isValidIsoDateTime', () => {
+    it('accepte un datetime ISO complet valide', () => {
+      expect(isValidIsoDateTime('2026-05-20T14:30:00')).toBe(true)
+      expect(isValidIsoDateTime('2026-01-01T00:00:00')).toBe(true)
+      expect(isValidIsoDateTime('2026-12-31T23:59:59')).toBe(true)
+    })
+
+    it('rejette une date seule, des composants invalides ou une chaîne vide', () => {
+      expect(isValidIsoDateTime('2026-05-20')).toBe(false)
+      expect(isValidIsoDateTime('2026-13-01T00:00:00')).toBe(false)
+      expect(isValidIsoDateTime('2026-05-20T24:00:00')).toBe(false)
+      expect(isValidIsoDateTime('2026-05-20T14:60:00')).toBe(false)
+      expect(isValidIsoDateTime('2026-05-20T14:30:60')).toBe(false)
+      expect(isValidIsoDateTime('2026-05-20T14:30')).toBe(false)
+      expect(isValidIsoDateTime('')).toBe(false)
+    })
+  })
+
+  describe('formatIsoDateTimeToDisplay', () => {
+    it('formate un datetime valide en JJ/MM/AAAA HH:MM', () => {
+      expect(formatIsoDateTimeToDisplay('2026-05-20T14:30:00')).toBe('20/05/2026 14:30')
+    })
+
+    it('renvoie une chaîne vide pour nul ou invalide', () => {
+      expect(formatIsoDateTimeToDisplay(null)).toBe('')
+      expect(formatIsoDateTimeToDisplay('2026-05-20')).toBe('')
+      expect(formatIsoDateTimeToDisplay('nope')).toBe('')
+    })
+  })
+
+  describe('splitDateTime', () => {
+    it('découpe un datetime valide', () => {
+      expect(splitDateTime('2026-05-20T14:30:00')).toEqual({date: '2026-05-20', time: '14:30'})
+    })
+
+    it('renvoie date null et time vide pour nul, date seule ou invalide', () => {
+      expect(splitDateTime(null)).toEqual({date: null, time: ''})
+      expect(splitDateTime('2026-05-20')).toEqual({date: null, time: ''})
+      expect(splitDateTime('nope')).toEqual({date: null, time: ''})
+    })
+  })
+
+  describe('composeDateTime', () => {
+    it('recompose un datetime ISO avec secondes à 00', () => {
+      expect(composeDateTime('2026-05-20', '14:30')).toBe('2026-05-20T14:30:00')
+    })
+
+    it('utilise 00:00 quand l\'heure est vide', () => {
+      expect(composeDateTime('2026-05-20', '')).toBe('2026-05-20T00:00:00')
+    })
+  })
+})