feat(ui) : add task list view with bulk actions, filters, and priority flag

- Add TaskListItem component with checkbox, project color, priority flag
- Add TaskBulkActions toolbar (bulk status/user/priority/effort/group update, delete)
- Add list view toggle button in my-tasks and project pages
- Add Priorité and Effort filters to project page
- TaskCard supports showProjectColor prop (color in my-tasks, neutral in project)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/components/task/TaskCard.vue

@@ -9,7 +9,12 @@
         <div class="flex items-start justify-between gap-2">
             <div class="min-w-0">
                 <div class="flex items-center gap-1">
-                    <span v-if="task.project && task.number" class="text-xs font-semibold" :style="{ color: task.project.color }">{{ task.project.code }}{{ task.number }}</span>
+                    <span
+                        v-if="task.project && task.number"
+                        class="text-xs font-semibold"
+                        :class="showProjectColor ? '' : 'text-neutral-400'"
+                        :style="showProjectColor && task.project.color ? { color: task.project.color } : {}"
+                    >{{ task.project.code }}{{ task.number }}</span>
                     <Icon
                         v-if="task.priority?.label === 'Haute'"
                         name="mdi:flag-variant"
@@ -68,9 +73,12 @@
 <script setup lang="ts">
 import type { Task } from '~/services/dto/task'
 
-const props = defineProps<{
+const props = withDefaults(defineProps<{
     task: Task
-}>()
+    showProjectColor?: boolean
+}>(), {
+    showProjectColor: false,
+})
 
 const emit = defineEmits<{
     (e: 'click'): void