[建议 / Feature] Option to hide projects with no sessions from the project list

提交前确认 · Pre-submission checklist

• I searched existing issues and confirmed this isn't a duplicate.
• I've read CONTRIBUTING.md.

问题类别 · Category

UI / 界面体验 · UI / UX

涉及的 Agent 框架 · Agent framework

ZCode Agent（自研）

使用场景 · Use case

The sidebar/project list in ZCode Desktop shows every workspace folder that has ever been opened — including folders where no session was ever created. Typical cases: a folder opened just to peek at one file, a repo added ahead of an upcoming task, or a folder that was later deleted/renamed on disk. These session-less projects can't be hidden or removed from the list, so over a few weeks the sidebar turns into a dump of dead entries and the active projects get harder to spot.

Current workaround is "only open folders you actually plan to work in", which isn't practical — opening a folder is also how you browse it.

建议方案 · Proposal

1. Per-project "Hide" action — a context-menu item on a project entry in the sidebar that removes it from the list without deleting anything; hidden projects are restorable from a "Manage projects" panel (or a settings section).
2. "Hide projects with no sessions" toggle/filter — either a filter control on the project list or a global setting, so zero-session projects are hidden by default and appear only in the manage view.
3. (Optional) recency-aware ordering — projects with recent sessions stay at the top; zero-session or stale projects sink to the bottom or into a collapsed "Other" group.

预期价值 · Expected value

The sidebar stays focused on actually-active work, which matters most for users juggling many client repos/scratch folders. Hiding is purely a list-level operation — sessions, history and files stay untouched — so it's low-risk to implement and immediately reduces clutter.

你认为的优先级 · Your perceived priority

中 · Medium

你使用的 ZCode 版本 / 环境 · ZCode version / environment

ZCode CLI v0.16.5 / ZCode Desktop, macOS 15 (Apple Silicon)

补充材料 · Additional context

• Hide should also cover projects whose folders were deleted or moved outside ZCode — today those linger with no way to clean them up from the UI.
• All three sub-features are independently shippable; #1 and #2 share the same "hidden projects" state.

No implementation files or tests are named. Start by reading CONTRIBUTING.md, then trace the Desktop sidebar/project list and the state that records projects and sessions; confirm with maintainers whether the per-project hide action, no-session filter, or recency ordering is in scope. Done should match the selected behavior while preserving sessions, history, and files.