feat(select) : anneau focus clavier, navigation APG et focus conservé après sélection

- Anneau de focus clavier (clavier-only) ; ouvert, l'anneau entoure
  bouton + liste d'un seul tenant, adapté au sens d'ouverture (haut/bas)
- Navigation clavier WAI-ARIA APG (manquait) : ouverture, flèches avec
  scroll auto de l'option active, Home/End, Entrée/Espace, Échap, Tab
- aria-activedescendant pour les lecteurs d'écran
- Le focus reste sur le bouton après sélection (plus de blur vers le body)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/components/malio/select/Select.vue

@@ -37,15 +37,24 @@
           twMerge(label ? 'min-h-[40px]' : 'h-[40px] py-0', fieldClass),
           rounded,
           textField,
+          keyboardFocused
+            ? (isOpen
+              ? (openDirection === 'down' ? 'm-combo-ring-top' : 'm-combo-ring-bottom')
+              : 'm-focus-ring-kbd')
+            : '',
   ]"
       :aria-expanded="isOpen"
       :aria-controls="listboxId"
+      :aria-activedescendant="isOpen && activeIndex >= 0 ? optionId(activeIndex) : undefined"
       :aria-invalid="hasError"
       :aria-describedby="describedBy"
       :aria-required="required || undefined"
       :aria-readonly="isReadonly || undefined"
       :disabled="disabled"
       @click="toggle"
+      @keydown="onKeydown"
+      @focus="onKbdFocus"
+      @blur="onKbdBlur"
     >
       <label
         v-if="label"
@@ -134,7 +143,10 @@
           ? 'border-m-danger'
           : hasSuccess
             ? 'border-m-success'
-            : 'border-m-primary'
+            : 'border-m-primary',
+        keyboardFocused
+          ? (openDirection === 'down' ? 'm-combo-ring-bottom' : 'm-combo-ring-top')
+          : '',
       ]"
     >
       <li
@@ -184,13 +196,16 @@
 </template>
 
 <script setup lang="ts">
-import {computed, onBeforeUnmount, onMounted, ref, useId, nextTick} from 'vue'
+import {computed, onBeforeUnmount, onMounted, ref, useId, nextTick, watch} from 'vue'
 import {Icon as IconifyIcon} from '@iconify/vue'
 import {twMerge} from 'tailwind-merge'
 import MalioRequiredMark from '../shared/RequiredMark.vue'
+import {useKbdFocusRing} from '../shared/useKbdFocusRing'
 
 defineOptions({name: 'MalioSelect', inheritAttrs: false})
 
+const {keyboardFocused, onFocus: onKbdFocus, onBlur: onKbdBlur} = useKbdFocusRing()
+
 type Option = {
   label: string;
   value: string | number | null
@@ -344,7 +359,68 @@ function toggle() {
 function select(value: string | number | null) {
   emit('update:modelValue', value)
   close()
-  buttonRef.value?.blur()
+  // On garde le focus sur le bouton après sélection (APG) : le focus ne doit pas
+  // retomber sur le body. La souris le conserve déjà via @mousedown.prevent sur
+  // les options ; au clavier le focus n'a jamais quitté le bouton.
+  buttonRef.value?.focus()
+}
+
+// Garde l'option active visible quand on navigue au clavier
+watch(activeIndex, async (index) => {
+  if (index < 0 || !isOpen.value) return
+  await nextTick()
+  document.getElementById(optionId(index))?.scrollIntoView({block: 'nearest'})
+})
+
+function onKeydown(e: KeyboardEvent) {
+  if (props.disabled || props.readonly) return
+
+  // Tab : laisse le focus partir mais ferme la liste
+  if (e.key === 'Tab') {
+    if (isOpen.value) close()
+    return
+  }
+
+  // Liste fermée : ouverture au clavier
+  if (!isOpen.value) {
+    if (e.key === 'ArrowDown' || e.key === 'ArrowUp' || e.key === 'Enter' || e.key === ' ') {
+      e.preventDefault()
+      open()
+    }
+    return
+  }
+
+  // Liste ouverte
+  if (e.key === 'Escape') {
+    e.preventDefault()
+    close()
+    return
+  }
+  if (e.key === 'Enter' || e.key === ' ') {
+    e.preventDefault()
+    const opt = normalizedOptions.value[activeIndex.value]
+    if (opt) select(opt.value)
+    return
+  }
+  if (e.key === 'ArrowDown') {
+    e.preventDefault()
+    activeIndex.value = Math.min(activeIndex.value + 1, normalizedOptions.value.length - 1)
+    return
+  }
+  if (e.key === 'ArrowUp') {
+    e.preventDefault()
+    activeIndex.value = Math.max(activeIndex.value - 1, 0)
+    return
+  }
+  if (e.key === 'Home') {
+    e.preventDefault()
+    activeIndex.value = 0
+    return
+  }
+  if (e.key === 'End') {
+    e.preventDefault()
+    activeIndex.value = normalizedOptions.value.length - 1
+  }
 }
 
 function onClickOutside(e: MouseEvent) {