Fix four things found by looking at the tabbed page

SOFTWARE OPENED COLLAPSED. The installed-software panel was collapsible and
started that way, because it used to be low-priority reference data near the
bottom of one long page. It is now the Software tab's whole reason to exist,
and somebody who clicked that tab has already said what they came for. Made
it neither collapsible nor collapsed.

TRACKED SERVICES VANISHED FROM METRICS. The group is decided by the SERVER, so
a new frontend against a server still serving the old vocabulary puts a panel
in a group the build does not render, and it is fetched, held, and shown
nowhere - with nothing logged. Moving services out of 'actions' is exactly that
shape. The client now falls back to 'details' for any group it does not render,
the same way the server does, so a version-skewed pair degrades to a misplaced
card instead of a missing one.

A TABLE PANEL WITH NOTHING IN IT HID ITSELF. panelVisible honoured `empty` for
list panels and ignored it for tables, for no reason anybody wrote down. A
declared empty message is an answer - "No installed software reported." - where
an absent card is a question. It matters more now that a panel can be the only
thing in a tab, because the tab disappears with it.

THE TAB STRIP HAD A VERTICAL SCROLLBAR. Per the overflow spec, when one axis is
not `visible` the other computes from `visible` to `auto`, so `overflow-x: auto`
alone made the strip scrollable vertically too and the -1px margin the tabs use
to sit on the border was enough to trip it.

Also moved .detail-full into the global stylesheet next to .content-grid, per
frontend/CLAUDE.md: it is detail-page layout, and the other four detail pages
need it when they adopt tabs.

Scope: product

plugins/computers/frontend/views/PCDetail.vue

@@ -603,11 +603,6 @@ async function confirmRetire() {
 </script>
 
 <style scoped>
-/* Software and Activity are single long lists, so they use the full page width
-   rather than .content-grid's two balanced columns. Cards inside still need
-   their own vertical rhythm, which the column flow was providing. */
-.detail-full { display: flex; flex-direction: column; gap: 1rem; }
-.detail-full > * { min-width: 0; }
 
 /* PC-specific styles - shared styles are in global style.css */