feat(absence) : extract Absence front into Nuxt module layer

LST-66 (2.3) front. Companion to the backend module migration.

- Move pages (absences, team-absences), 8 components, the absences service +
  DTO and the useAbsenceHelpers composable into frontend/modules/absence/
  (auto-detected layer; composable now auto-imported).
- Rewrite consumers: AdminAbsencePolicyTab and the time-tracking calendar
  (getPublicHolidays) point to ~/modules/absence/...
- Middlewares (employee/admin) and shared services (clients, users,
  user-data DTO) stay at the root. i18n stays global.
- Routes /absences and /team-absences preserved.

nuxt build passes; routes confirmed.

frontend/modules/absence/components/AbsenceBalanceAdjustDrawer.vue

@@ -0,0 +1,69 @@
+<template>
+    <MalioDrawer v-model="open" drawer-class="max-w-md">
+        <template #header>
+            <h2 class="text-xl font-bold">{{ $t('absences.admin.adjust.title') }}</h2>
+        </template>
+        <div v-if="balance" class="flex flex-col gap-4">
+            <p class="text-sm text-neutral-600">
+                {{ balance.user.username }} · {{ balance.label }} · {{ balance.period }}
+            </p>
+            <MalioInputNumber v-model="acquired" :label="$t('absences.admin.adjust.acquired')" />
+            <MalioInputNumber v-model="acquiring" :label="$t('absences.admin.adjust.acquiring')" />
+            <MalioInputNumber v-model="taken" :label="$t('absences.admin.adjust.taken')" />
+            <div class="flex justify-end gap-2 pt-2">
+                <MalioButton :label="$t('common.cancel')" variant="tertiary" @click="open = false" />
+                <MalioButton :label="$t('absences.admin.adjust.save')" :disabled="submitting" @click="submit" />
+            </div>
+        </div>
+    </MalioDrawer>
+</template>
+
+<script setup lang="ts">
+import type { AbsenceBalance } from '~/modules/absence/services/dto/absence'
+import { useAbsenceService } from '~/modules/absence/services/absences'
+
+const props = defineProps<{
+    modelValue: boolean
+    balance: AbsenceBalance | null
+}>()
+
+const emit = defineEmits<{
+    'update:modelValue': [value: boolean]
+    'adjusted': []
+}>()
+
+const service = useAbsenceService()
+
+const open = computed({
+    get: () => props.modelValue,
+    set: (v) => emit('update:modelValue', v),
+})
+
+// MalioInputNumber works with string values (v-model is string | null).
+const acquired = ref('0')
+const acquiring = ref('0')
+const taken = ref('0')
+const submitting = ref(false)
+
+watch(() => props.balance, (b) => {
+    acquired.value = String(b?.acquired ?? 0)
+    acquiring.value = String(b?.acquiring ?? 0)
+    taken.value = String(b?.taken ?? 0)
+}, { immediate: true })
+
+async function submit() {
+    if (!props.balance) return
+    submitting.value = true
+    try {
+        await service.adjustBalance(props.balance.id, {
+            acquired: Number(acquired.value) || 0,
+            acquiring: Number(acquiring.value) || 0,
+            taken: Number(taken.value) || 0,
+        })
+        emit('adjusted')
+        open.value = false
+    } finally {
+        submitting.value = false
+    }
+}
+</script>