[VS Code extension] Session history: show absolute dates, and let sessions be pinned

Two small additions to the session history list in the VS Code extension.

1. Show an absolute date, not just relative time

The list shows only relative time (now, 5m, 2h, 3d, 2mo, 1y). When deciding which past session to resume, the question is almost always "when did I last work on this?" — and once you have dozens of sessions, 3d vs 2mo isn't enough to tell them apart.

It's also hidden the moment you reach for the row:

.sessionItem:hover .sessionMeta:has(.sessionActions) .sessionTime { visibility: hidden }

The rename/delete buttons take that spot, so moving the mouse toward a session makes the only piece of time information disappear.

Suggestion: Today 14:32 / Yesterday 09:05 / 07.30 (Wed) / 25.12.30 (Tue), or keep the relative time and expose the absolute date as a tooltip.

2. Let sessions be pinned

There's no way to keep frequently revisited sessions at hand — they scroll away as new ones accumulate. The workaround I'd been using is pinning the editor tab, which only helps while the session is open.

Suggestion: a pin toggle on each row, plus a filter for pinned sessions alongside the existing Local / Web tabs.

Why I'm filing this

Two of us on the same team ran into both of these independently and each ended up patching the extension bundle locally — one of us had been doing it for a long time before we compared notes. That's what convinced me it's worth reporting rather than just keeping the local patch.

Version: VS Code extension 2.1.220, Windows 11