make the yazi popup remember state

[luccahuguet]

Problem

Within one Nova tab, hiding the managed Yazi popup and showing it again can lose the popup's navigation state.

Expected behavior

Ordinary Alt Shift Y toggles preserve the same live Yazi process and navigation while the tab's canonical workspace root is unchanged.

• Navigation equal to or below the tab root should survive hide/show.
• A real tab-root change may replace the popup.
• If launch identity is unavailable and the live popup has left the tab root, the next toggle may restart it at the root.
• yzx reveal remains an explicit replacement at its requested target.

Ownership

The pane orchestrator remains the sole owner of the canonical tab root. yzpp owns popup launch identity and hide/show/replacement. The fix should not add separate Git-root detection, polling, or another workspace owner.

Investigation note

yzpp remembers popup launch cwd, but when that identity is unavailable it falls back to exact live-process cwd comparison. A popup launched at /repo and navigated to /repo/src can therefore appear stale after plugin reconfiguration. This is a source-backed hypothesis, not yet the accepted cause; reproduce it first.

Tracked in Beads as yazelix-5vl-kz48.