feat : composant MalioDate (datepicker) avec calendrier, vue mois, bornes et effacement (#MUI-33)

Sous-composants internes (CalendarHeader, MonthGrid, MonthPicker), composant
public Date.vue, tests d'intégration, story Histoire et page playground.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/components/malio/date/internal/MonthPicker.vue

@@ -0,0 +1,32 @@
+<template>
+  <div
+    data-test="month-picker"
+    class="grid grid-cols-4 gap-2 p-3"
+  >
+    <button
+      v-for="(name, index) in monthsShort"
+      :key="name"
+      type="button"
+      data-test="month"
+      :data-month="index"
+      class="rounded py-3 text-sm transition-colors duration-100"
+      :class="index === selectedMonth
+        ? 'bg-m-primary text-white'
+        : 'text-black hover:bg-m-primary/10'"
+      @click="emit('select', index)"
+    >
+      {{ name }}
+    </button>
+  </div>
+</template>
+
+<script setup lang="ts">
+defineOptions({name: 'MalioDateMonthPicker'})
+
+defineProps<{selectedMonth?: number}>()
+
+const emit = defineEmits<{(e: 'select', month: number): void}>()
+
+const monthsShort = ['Janv', 'Févr', 'Mars', 'Avr', 'Mai', 'Juin',
+  'Juil', 'Août', 'Sept', 'Oct', 'Nov', 'Déc']
+</script>