Tab the PC detail page, and let a panel say which tab it belongs to

The page had grown to roughly ten cards in one flow, and three more surfaces
were wanted on it: installed software, live metrics, and the service controls.
Stacking those into the same column would have buried what the page is for.

Tabs were mocked and rejected on 2026-08-28, on the grounds that the strip
duplicated the sidebar and cost hero space. That objection is answered by
where the strip sits: the hero and the triage band stay above it and never
move, so "is this machine OK" is still answered without a click, and the strip
partitions the detail underneath rather than navigating anywhere.

WHY A PANEL DECLARES ITS OWN GROUP

Most cards on a detail page are not the page's. They arrive through the
ADR-010 get_asset_panels hook, so a page that sorted panels into tabs by
knowing their ids would defeat the hook it is built on. Panels now carry an
optional group instead, and the page only knows the five group names.

Resolution happens server-side, in the asset-panels route, so that an absent
or misspelled group becomes 'details' before the client ever sees it. The
client renders known groups only; an unrecognised value that survived to it
would be a panel that exists and is displayed nowhere. Contract 0.28.0 ->
0.29.0, additive - every existing plugin keeps working untouched, and the
endpoints status panel is deliberately left ungrouped so the default path is
exercised by a shipped plugin and not only by tests.

A tab is offered only when something fills it. An empty tab reads as broken
rather than as "this site does not collect that", so the strip is built from
the groups that actually returned data, and a tab that disappears on refetch
falls back to Details rather than leaving the page blank.

AssetDetailTabs is core, not a PCDetail component: machines, printers,
network devices and measuring tools all have the same shape, and the shared
asset-detail shell they need starts here.

Scope: product

docs/CONTRACT-STABILITY.md

@@ -47,6 +47,7 @@ Recorded in the comment block in `shopdb/__init__.py`:
 | 0.25.0 | Added `caller_holds(permission)`, which answers whether the current caller holds a permission WITHOUT refusing the request - the complement to `require_permission` for a route that serves everyone but should only offer what the caller can act on. The endpoints services panel is the case: it emitted Start/Stop row actions to every reader, because the emission never consulted the caller. Clicking them was always refused server-side, so nothing was exploitable, but offering a read-only viewer controls over a shop-floor PC is the wrong signal, and it becomes a real problem once a site grants that panel to guests. Guests are included in the answer, since a signed-out visitor holds whatever the guest role was granted | additive surface (minor) |
 | 0.26.0 | Dashboard cards may declare `shortname`. The dashboard merged its per-source cards into one worst-first queue, and a card's `title` is written as a heading ("Endpoints with crashes or shutdowns") which as a row badge ran wider than the hostname it qualified. Optional, defaults to the title, so a plugin that does not declare one is unaffected | additive field (minor) |
 | 0.27.0 | Added `Script` so a plugin can read the ShopDB-hosted script library that backs endpoint `run_script` delivery without importing core model internals. The endpoints plugin resolves a delivered script by name and serves its body by digest to the agent | additive surface (minor) |
+| 0.29.0 | Added an optional `group` to `get_asset_panels`, naming which detail-page tab a panel belongs to: `details` (the default) / `software` / `metrics` / `actions` / `activity`. The detail pages are tabbed, and a page that placed panels by knowing their ids would defeat the hook. Additive: an absent or unrecognised group resolves to `details` server-side, so every existing plugin keeps working with no change | additive surface (minor) |
 | 0.28.0 | Added `client_ip` and `strip_port` so a plugin does not hand-roll caller-IP extraction. Two plugins had, and both read the first `X-Forwarded-For` hop, which the caller supplies - so a rate limit keyed on it was defeated by rotating the header. The helper resolves from `remote_addr`, which ProxyFix has already filled from the header when `TRUSTED_PROXY_COUNT` says a proxy is really in front | additive surface (minor) |
 
 The source comment block documents 0.3.0, 0.4.0, 0.6.0, 0.7.0, 0.9.0, 0.10.0,