vscode: migrate Recently Closed view from sidebar to Codev panel tab

[amrmelsayed]

Problem

The Recently Closed view (packages/vscode/src/views/recently-closed.ts) lives in the Codev sidebar today, occupying vertical real estate alongside the higher-frequency Builders / Backlog / Pull Requests views. Its content is chronological — a timeline of recently closed issues and PRs — which fits the wide-short geometry of the bottom panel better than the narrow-tall sidebar, and it's a less-frequent reference surface so a less-prominent dock matches its priority.

Proposed behavior

Migrate the existing codev.recentlyClosed view from the codev (sidebar) container to the new codevPanel (panel) container introduced in #812. No data, rendering, or interaction changes — same TreeDataProvider, same row shape, same context menu actions. Only the container id changes.

Implementation

1. In packages/vscode/package.json, move the codev.recentlyClosed entry from contributes.views.codev to contributes.views.codevPanel.
2. Update any view/title menu entries that reference view == codev.recentlyClosed — they don't change (still keyed by the view id), but verify they still render in the new container's title bar.
3. Update view/item/context entries (if any) — same view id, no change needed.
4. Smoke-test: ensure the view still updates reactively on OverviewCache SSE ticks (the provider doesn't depend on which container hosts it).

Acceptance criteria

• codev.recentlyClosed registered under viewsContainers.panel.codevPanel, not under activitybar.codev.
• Recently Closed tab no longer appears in the Codev sidebar.
• Tab appears in the Codev panel area, fully functional (rows render, click actions work, SSE refresh works).
• view/title and view/item/context actions that target this view still fire correctly.
• No regression to other Codev views (sidebar or panel).

Depends on

• vscode: introduce a Codev panel tab (bottom-area view container) to relieve sidebar overload #812 — Codev panel container scaffolding must land first.

Out of scope

• Re-rendering Recently Closed as a horizontal timeline / webview (could be a follow-up; v1 is the same TreeView in a new home).
• Adding new actions to the view.