Add project soft-delete with workspace archival

- Add delete button (×) to sidebar project list, shown on hover
- Soft-delete: mark projects as deleted in DB instead of hard delete
- Move workspace files to /app/data/deleted/ folder on deletion
- Filter deleted projects from list query
- Auto-select next project after deleting current one
- Also includes agent prompt improvements for reverse proxy paths

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/components/AppLayout.vue

@@ -80,6 +80,23 @@ function onProjectUpdate(projectId: string, name: string) {
   const p = projects.value.find(p => p.id === projectId)
   if (p) p.name = name
 }
+
+async function onDeleteProject(id: string) {
+  try {
+    await api.deleteProject(id)
+    projects.value = projects.value.filter(p => p.id !== id)
+    if (selectedProjectId.value === id) {
+      selectedProjectId.value = projects.value[0]?.id ?? ''
+      if (selectedProjectId.value) {
+        history.replaceState(null, '', `/projects/${selectedProjectId.value}`)
+      } else {
+        history.replaceState(null, '', '/')
+      }
+    }
+  } catch (e: any) {
+    error.value = e.message
+  }
+}
 </script>
 
 <template>
@@ -92,6 +109,7 @@ function onProjectUpdate(projectId: string, name: string) {
       :selectedId="selectedProjectId"
       @select="onSelectProject"
       @create="onStartCreate"
+      @delete="onDeleteProject"
     />
     <main class="main-content">
       <div v-if="error" class="error-banner" @click="error = ''">{{ error }}</div>