Export: tasks in top-level folder, smart search expansion

- Move all tasks to top-level tasks/ folder (no longer nested under
  projects/slug/tasks/). The project slug is still in the frontmatter
  for association.
- Search auto-expands parent dirs of matched files so matches are
  always visible in the tree
- Restores previous expansion state when search is cleared
- All files already loaded in memory — search works across everything
  with no pagination limit

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/services/company-portability.ts

@@ -1758,9 +1758,8 @@ export function companyPortabilityService(db: Db) {
     for (const issue of selectedIssueRows) {
       const taskSlug = taskSlugByIssueId.get(issue.id)!;
       const projectSlug = issue.projectId ? (projectSlugById.get(issue.projectId) ?? null) : null;
-      const taskPath = projectSlug
-        ? `projects/${projectSlug}/tasks/${taskSlug}/TASK.md`
-        : `tasks/${taskSlug}/TASK.md`;
+      // All tasks go in top-level tasks/ folder, never nested under projects/
+      const taskPath = `tasks/${taskSlug}/TASK.md`;
       const assigneeSlug = issue.assigneeAgentId ? (idToSlug.get(issue.assigneeAgentId) ?? null) : null;
       files[taskPath] = buildMarkdown(
         {