feat(webui): rate badges, refresh labels, anchor links

Providers tab (Feature A): a new ProviderRateBadge component renders
each provider's day-window success rate (attempts-failures)/attempts —
always shown when attempts>0 (100% muted, <99% amber via the chart
palette's --color-chart-tokens-out token, <90% destructive, reusing the
Badge component's existing secondary/outline/destructive idioms rather
than inventing a new variant), a distinct "no traffic" badge when
attempts=0, and the live minute-window count in its title attribute.
The same component renders beside a ModelChip inside a provider's
accordion, but only when that model is degraded (<99% with attempts>0)
so a long, healthy model list stays uncluttered. The math and its
threshold constants live in lib/provider-rate.ts, unit-tested directly
(vitest's node environment needs no component mount).

Feature B: a provider's "refreshed ..." label (lib/format.ts's new
refreshLabel) now reads "discovery off" when DiscoveryEnabled is false,
"pending" when it is true but lastRefresh is still unset, and otherwise
the unchanged relative-time text — replacing the misleading "refreshed
never" a discovery-disabled provider showed before.

Feature C: composables/useTabHash syncs App.vue's active tab to the URL
hash (#providers/#usage/#charts/#targets, matching the existing
TabsTrigger values) with no router dependency. On load it reads the
current hash (falling back to "providers" for an absent or invalid one);
on tab change it writes the hash back via history.replaceState (no
scroll jump, no new history entry per click); a hashchange listener
handles back/forward and hand-edited URLs. hashToTab/tabToHash are
exported as pure functions so the mapping is unit-tested directly,
independent of window/history/location — every DOM touch inside
useTabHash itself is guarded behind one hasWindow check so the module
still imports cleanly under vitest's node test environment.
AuthGate never reads or writes the hash, so a tab named in the URL
survives the unauthenticated -> authenticated transition unchanged.

webui/src/components/ProvidersView.vue

@@ -9,6 +9,7 @@ import { computed, h, reactive, watch } from 'vue'
 
 import DataTable from '@/components/DataTable.vue'
 import ModelChip from '@/components/ModelChip.vue'
+import ProviderRateBadge from '@/components/ProviderRateBadge.vue'
 import SearchInput from '@/components/SearchInput.vue'
 import { Accordion, AccordionContent, AccordionItem, AccordionTrigger } from '@/components/ui/accordion'
 import { Badge } from '@/components/ui/badge'
@@ -20,10 +21,11 @@ import {
   CardTitle,
 } from '@/components/ui/card'
 import { useSearchQuery } from '@/composables/useSearchQuery'
-import { formatAgo, formatTimestamp, routableModelId } from '@/lib/format'
+import { formatAgo, formatTimestamp, refreshLabel, routableModelId } from '@/lib/format'
+import { isModelDegraded } from '@/lib/provider-rate'
 import { type ExpandState, clearExpandOverrides, computeExpandedItems, toggleItemExpand } from '@/lib/search-expand'
 import { useDashboardStore } from '@/stores/dashboard'
-import type { AdminAliasView, AdminProviderView } from '@/types/api'
+import type { AdminAliasView, AdminModelRateView, AdminProviderView } from '@/types/api'
 
 // This component backs the "Providers" tab (App.vue) — a UI-label rename
 // only. The data it renders still comes from GET /admin/api/overview
@@ -136,6 +138,20 @@ function visibleModels(p: AdminProviderView): string[] {
   return hasQuery.value ? p.models.filter((m) => modelMatches(p.name, m)) : p.models
 }
 
+/** ZERO_MODEL_RATE is the fallback ProviderRateBadge reads for a model p.modelRates has no entry for — should not happen (admin.go's buildAdminOverview populates one entry per Models id, unconditionally), but a defensive fallback keeps a stale/mismatched client build from throwing rather than just under-reporting. */
+const ZERO_MODEL_RATE: AdminModelRateView = { attemptsDay: 0, failuresDay: 0, attemptsMinute: 0, failuresMinute: 0 }
+
+/** modelRateFor looks up one model's counters within p.modelRates (Feature A, v0.22), falling back to ZERO_MODEL_RATE. */
+function modelRateFor(p: AdminProviderView, model: string): AdminModelRateView {
+  return p.modelRates[model] ?? ZERO_MODEL_RATE
+}
+
+/** modelIsDegraded gates the per-model rate badge (spec: "ONLY when that model is degraded") so a healthy or no-traffic model's ModelChip renders with no badge beside it at all. */
+function modelIsDegraded(p: AdminProviderView, model: string): boolean {
+  const r = modelRateFor(p, model)
+  return isModelDegraded(r.attemptsDay, r.failuresDay)
+}
+
 // --- model aliases (sortable DataTable, operator directive) ---
 //
 // The alias id gets the ModelChip copy treatment (an alias name IS the
@@ -244,13 +260,19 @@ const aliasEmptyMessage = computed(() =>
                 <span class="font-medium">{{ p.name }}</span>
                 <Badge as="span" variant="secondary" class="font-normal">{{ p.type }}</Badge>
                 <span class="text-xs text-muted-foreground tabular-nums">{{ p.modelCount }} models</span>
+                <ProviderRateBadge
+                  :attempts-day="p.attemptsDay"
+                  :failures-day="p.failuresDay"
+                  :attempts-minute="p.attemptsMinute"
+                  :failures-minute="p.failuresMinute"
+                />
                 <FontAwesomeIcon
                   v-if="p.lastErr"
                   :icon="faTriangleExclamation"
                   class="size-3.5 shrink-0 text-destructive"
                   aria-hidden="true"
                 />
-                <span class="text-xs text-muted-foreground">refreshed {{ formatAgo(p.lastRefresh) || 'never' }}</span>
+                <span class="text-xs text-muted-foreground">{{ refreshLabel(p.discoveryEnabled, p.lastRefresh) }}</span>
               </span>
             </AccordionTrigger>
             <AccordionContent>
@@ -269,7 +291,16 @@ const aliasEmptyMessage = computed(() =>
                 </div>
               </dl>
               <div v-if="visibleModels(p).length" class="flex flex-wrap gap-1.5">
-                <ModelChip v-for="m in visibleModels(p)" :key="m" :id="routableModelId(p.name, m)" />
+                <span v-for="m in visibleModels(p)" :key="m" class="inline-flex items-center gap-1">
+                  <ModelChip :id="routableModelId(p.name, m)" />
+                  <ProviderRateBadge
+                    v-if="modelIsDegraded(p, m)"
+                    :attempts-day="modelRateFor(p, m).attemptsDay"
+                    :failures-day="modelRateFor(p, m).failuresDay"
+                    :attempts-minute="modelRateFor(p, m).attemptsMinute"
+                    :failures-minute="modelRateFor(p, m).failuresMinute"
+                  />
+                </span>
               </div>
               <p v-else class="text-sm text-muted-foreground">no models known yet</p>
             </AccordionContent>