feat(web): coquille IDE + arbre de projets unifié (route /ide)

components/ide/ : IdeShell (grille barre d'activité + panneau gauche + zone centrale + dock + barre de statut, splitters persistés, réconciliation des ressources ouvertes contre les données live), ActivityBar (Explorer/Git/Sessions/Groupes + Réglages/Aide), PrimarySidebar, ProjectTree + ProjectTreeNode (arbre unique repos -> worktrees -> sessions, fichiers embarqués via FileTree en mode sans chrome, dépliage paresseux), StatusBar.

Route /ide (layout 'ide'), entrée de nav « IDE », namespace i18n ide (EN/FR). Clics de l'arbre pilotent le store (contexte worktree, ouverture de fichier/terminal). Centre et dock en placeholders (remplis en B4/B5). FileTree gagne un mode embedded. 427 tests.

packages/web/src/components/ide/ProjectTree.vue

@@ -0,0 +1,69 @@
+<template>
+  <div class="flex h-full min-h-0 flex-col">
+    <div class="flex items-center gap-1 px-3 py-2 text-[11px] font-semibold tracking-wide text-fg-subtle uppercase">
+      {{ t('ide.projects') }}
+      <button
+        type="button"
+        class="ml-auto rounded p-0.5 hover:bg-surface-2 hover:text-fg"
+        :title="t('repos.scan')"
+        :disabled="scanning"
+        @click="onScan"
+      >
+        <ScanSearch :size="14" />
+      </button>
+      <button type="button" class="rounded p-0.5 hover:bg-surface-2 hover:text-fg" :title="t('ide.addProject')" @click="showPicker = true">
+        <Plus :size="14" />
+      </button>
+    </div>
+
+    <div class="min-h-0 flex-1 overflow-auto pb-2">
+      <p v-if="repos.length === 0" class="px-3 py-2 text-xs text-fg-subtle">{{ t('ide.noProjects') }}</p>
+      <ProjectTreeNode v-for="repo in repos" :key="repo.id" :repo="repo" />
+    </div>
+
+    <DirectoryPicker v-if="showPicker" mode="repo" :initial-path="''" @select="onPick" @close="showPicker = false" />
+  </div>
+</template>
+
+<script setup lang="ts">
+import { computed, ref } from 'vue';
+import { useI18n } from 'vue-i18n';
+import { Plus, ScanSearch } from '@lucide/vue';
+import { useWorktreesStore } from '../../stores/worktrees';
+import { useToastsStore } from '../../stores/toasts';
+import ProjectTreeNode from './ProjectTreeNode.vue';
+import DirectoryPicker from '../DirectoryPicker.vue';
+
+const { t } = useI18n();
+const worktrees = useWorktreesStore();
+const toasts = useToastsStore();
+
+const showPicker = ref(false);
+const scanning = ref(false);
+
+const repos = computed(() =>
+  [...worktrees.repos].filter((r) => !r.hidden).sort((a, b) => a.label.localeCompare(b.label)),
+);
+
+async function onScan(): Promise<void> {
+  scanning.value = true;
+  try {
+    const res = await worktrees.discover();
+    toasts.success(t('repos.scanResult', res.added));
+  } catch (err) {
+    toasts.error(err);
+  } finally {
+    scanning.value = false;
+  }
+}
+
+async function onPick(path: string): Promise<void> {
+  showPicker.value = false;
+  try {
+    await worktrees.addRepo(path);
+    toasts.success(t('toast.repoAdded'));
+  } catch (err) {
+    toasts.error(err);
+  }
+}
+</script>