Bring Sloth Manager's DNS/Secrets dashboard here, alongside integrations

Sloth Manager's dashboard showed per-system stats for DNS and Secrets
(domains/records by type, expiry counts by type) that this app's
Dashboard never had -- it only ever showed the six live integration
widgets. Port those two sections over, generalized to sit alongside
the integrations this app added that Sloth Manager never had.

New server/src/dns/stats.ts (getDnsStats(), used by new GET
/api/dns/stats): zone counts are fetched live per enabled provider
(matching what the DNS page itself shows, since the zone cache table
only gets a row once a zone has been synced and would undercount) --
one unreachable provider surfaces its error without blanking the rest.
Record-type breakdown comes from the local cache instead, since
records are only ever shown from cache elsewhere in this app too
(fetching every zone's records live on every dashboard load would be
far more expensive for no real accuracy gain).

Dashboard.tsx gained three sections under clear headers: DNS (domain/
provider/record stat tiles + a "records by type" breakdown), Secrets
(monitored/expiring/expired tiles + a "secrets by type" breakdown,
computed client-side from the already-fetched secrets list, same as
Sloth Manager did), and the existing Integrations widgets grouped
under their own header for visual parity with the two new sections.
Breakdowns render as a stacked proportion bar with a color-coded
legend rather than a pie chart -- this app has no charting library
anywhere yet, and a plain CSS progress bar (an idiom Tabler itself
uses) gets the same "see the mix at a glance" value without adding one
for a single dashboard.

Verified getDnsStats() against a temp SQLite DB with real migrations
and an enabled + a disabled DNS provider: enabled/total provider
counts, live zone counting, and cached-record-type aggregation (sorted
by count) all came back correct, and the disabled provider was
correctly excluded from the zone count while still counting toward
the total.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web/src/api/client.ts

@@ -573,6 +573,15 @@ export const api = {
   dns: {
     providerFields: () =>
       request<{ fields: Record<DnsProviderType, DnsProviderField[]> }>("/api/dns/provider-fields"),
+    stats: () =>
+      request<{
+        totalProviders: number;
+        enabledProviders: number;
+        totalZones: number;
+        perProvider: { providerId: number; name: string; providerType: DnsProviderType; zoneCount: number; error: string | null }[];
+        totalRecords: number;
+        recordsByType: { type: string; count: number }[];
+      }>("/api/dns/stats"),
     providers: {
       list: () => request<{ providers: DnsProviderSummary[] }>("/api/dns/providers"),
       create: (data: { providerType: DnsProviderType; name: string; config: Record<string, string | boolean> }) =>