Explore: cards can be dragged out to the inbox

One-directional drag support, joining the shared "kanban" group:
put: false and sort: false mean a card can leave Explore's list (to
unfile it via the sidebar's inbox) but the list can't receive a drop
itself (there's no status to assign an incoming card) or be reordered
by dragging (it's sorted by name regardless).

sortedCards moves from a computed to a ref rebuilt by a watch --
<draggable> splices its bound list in place as the user drags, which a
plain computed would just discard on its next recomputation. No local
@change handler is needed: the splice already happens locally, and the
inbox's own handler (AppSidebar) persists the move and reloads this
project's cards regardless of which side of the drag it's reacting to.

AppSidebar: widened the "is a project open" check for the post-drag
cards refresh back to both project routes (Explore's list is now also
a place a card can leave from), and reused the same route-name set
already defined for the sidebar's project switcher.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web/src/views/ProjectExploreView.vue

@@ -1,8 +1,10 @@
 <script setup lang="ts">
-import { computed, ref } from 'vue'
+import { computed, ref, watch } from 'vue'
+import draggable from 'vuedraggable'
 import CardRow from '../components/CardRow.vue'
 import { ApiError } from '../lib/api'
 import { useCardsStore } from '../stores/cards'
+import type { Card } from '../types'
 
 // The project's cards, flat and sorted by name -- ProjectView (the parent
 // layout) has already loaded them into this store, keyed to the current
@@ -19,10 +21,16 @@ const summary = computed(() => {
   return `${total} card${total === 1 ? '' : 's'}.`
 })
 
-// No manual order here -- sort by name, case-insensitively.
-const sortedCards = computed(() =>
-  [...cards.cards].sort((a, b) => a.text.localeCompare(b.text, undefined, { sensitivity: 'base' })),
-)
+// No manual order here -- sorted by name, case-insensitively -- but a plain
+// computed can't be handed to <draggable> (it splices its bound list in
+// place as the user drags; a computed would just be recalculated over that
+// and discard it). A ref rebuilt on every underlying change gives it
+// something real to mutate, the same way the kanban board's columns do.
+const sortedCards = ref<Card[]>([])
+function rebuildSortedCards() {
+  sortedCards.value = [...cards.cards].sort((a, b) => a.text.localeCompare(b.text, undefined, { sensitivity: 'base' }))
+}
+watch(() => cards.cards, rebuildSortedCards, { deep: true, immediate: true })
 
 async function onCreate() {
   submitting.value = true
@@ -46,9 +54,26 @@ async function onCreate() {
 
     <p v-if="cards.loading && !cards.loaded" class="muted">Loading…</p>
 
-    <ul v-else-if="sortedCards.length" class="cards">
-      <CardRow v-for="card in sortedCards" :key="card.id" :card="card" />
-    </ul>
+    <!-- No handler needed: dragging a card out (the only thing possible --
+         put: false, sort: false) splices it out of `sortedCards` locally, and
+         wherever it lands (the sidebar's inbox) persists the move and
+         reloads this project's cards, which rebuilds this list from the
+         authoritative result either way. -->
+    <draggable
+      v-else-if="sortedCards.length"
+      :list="sortedCards"
+      :group="{ name: 'kanban', put: false }"
+      :sort="false"
+      item-key="id"
+      tag="ul"
+      class="cards"
+      ghost-class="card-row--ghost"
+      :animation="150"
+    >
+      <template #item="{ element: card }: { element: Card }">
+        <CardRow :card="card" />
+      </template>
+    </draggable>
 
     <form class="kanban__new form--new-card" @submit.prevent="onCreate">
       <input