[FEATURE] Sidebar: order the chats/tasks under an expanded pinned Project by last activity (or add a sort control)

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

In the merged Home sidebar, a pinned Project can be expanded to show its recent chats/tasks nested beneath it — currently the only per-project view available in the sidebar since Group by → Project was removed (#85930). But that nested list is not ordered by last activity, and there is no sort control on it.

The practical effect: when I'm creating several tasks in a project, or bouncing back and forth between tasks, the tasks I'm actively using end up buried deep in the nested list. The only reliable way to find an active task is to leave the sidebar, open the project's main page, and scan the full task list — which defeats the purpose of pinning and expanding the project, namely one-click access to what's in flight.

(I've described the list as "not ordered by last activity" from observed behavior; I have not been able to determine what order it does follow — it does not change as tasks are used.)

Proposed Solution

Either of:

1. Order the nested list under an expanded pinned Project by last activity (most recently used first), or
2. Add a sort control on that list (Recency / Manual), with the choice persisted.

Priority

Medium - Would be very helpful

Feature Category

UI/UX

Related Issues

• #75511 — pinned chats sort by recency on mobile but a frozen manual order on desktop; possibly the same persisted-order mechanism.
• #78233 — pinning a project removes its sessions from Recents; the complementary way pinned-project work gets buried.
• #85930 — Group by → Project removed from the merged Home (mine). This request is about ordering within one pinned project's nested list, so filing separately.

Additional Context

Claude Desktop 1.40609.0, macOS 26.5.1 (25F80), Apple Silicon.