ADR-013 Phase 3: generic asset-panels renderer (Path A)

Wires the ADR-010 get_asset_panels hook to a generic frontend renderer so a
plugin adds detail-page UI as JSON, no Vue. This is the Path A foundation that
lets simple plugins ship UI without a frontend build.

- components/PluginAssetPanels.vue + pluginAssetPanels.js: fetches
  /api/pluginui/asset-panels for an asset, then each panel's data endpoint, and
  renders by mode: list (title + status badge + meta lines via a field map),
  keyvalue, table (declared or inferred columns), badge. Pure mapping logic is
  in the .js module and unit tested (9 specs), same pattern as entryForm.js.
- New 'list' render mode with a declarative field map (title/badge/meta),
  documented on the hook in base.py.
- Warranty migrated to it: get_asset_panels now declares a 'list' panel + map
  that reproduces WarrantyPanel's output (vendor title, status badge with color
  + label map, servicelevel/ends/tag meta, manage link) with zero
  warranty-specific frontend code.
- MachineDetail swapped from <WarrantyPanel> to <PluginAssetPanels> (pilot); the
  hero warranty badge is unchanged. Verified end to end: the API serves the list
  panel + map and the warranty rows; the page renders without error.

Rollout of the other 4 detail pages (PCDetail, PrinterDetail, NetworkDeviceDetail,
MeasuringToolDetail) and the map-overlays / asset-presentation renderers are
follow-up Phase 3 commits. 58 vitest, build clean, 1067 backend pass, naming green.

plugins/warranty/plugin.py

@@ -83,7 +83,33 @@ class WarrantyPlugin(BasePlugin):
                 'title': 'Warranty',
                 'assettypes': ['*'],
                 'endpoint': '/api/warranty/asset/{assetid}',
-                'render': 'table',
+                'render': 'list',
+                # Field map: the generic renderer builds each list item from the
+                # warranty payload without any warranty-specific frontend code.
+                'map': {
+                    'title': 'vendor',
+                    'badge': {
+                        'label': 'status',
+                        'color': 'statuscolor',
+                        'labelmap': {
+                            'active': 'Active',
+                            'expiring': 'Expiring Soon',
+                            'expired': 'Expired',
+                            'unknown': 'Unknown',
+                        },
+                    },
+                    'meta': [
+                        {'key': 'servicelevel'},
+                        {'key': 'enddate', 'label': 'Ends', 'format': 'date'},
+                        {'key': 'servicetag', 'label': 'Tag', 'mono': True},
+                    ],
+                },
+                'empty': 'No warranty on record.',
+                'manage': {
+                    'to': '/warranties?addfor={assetid}',
+                    'label': 'Add / manage',
+                    'emptylabel': 'Add one',
+                },
                 'position': 30,
             },
         ]