feat(02-06): cache the Server tab's seven load groups with explicit TTL/persist

Server.vue already had five of the seven load groups (network summary, FIPS
summary, VPN peers, interfaces, Tor services) on useCachedResource from a
pre-phase commit, but none declared an explicit ttlMs/persist (relying on
the composable's 30s/persist:true defaults) and dedup:true was missing from
several underlying RPC calls. loadDiskStatus was the one remaining plain
uncached fetch, forced on every activation.

- Explicit TTL per group (10s fast tier: network-summary/interfaces/
  disk-status; 30s near-default: vpn-peers/tor-services; 60s near-static:
  fips-summary)
- Explicit persist:false for server.vpn-peers (npub/peer identity) and
  server.tor-services (onion addresses) per T-02-01; other groups persist
- New server.disk-status cached resource replaces the plain fetch; it now
  self-heals via the composable's own onActivated instead of an explicit
  every-entry call
- dedup:true added to all underlying rpcClient calls, including the
  parameterless vpnStatus()/dnsStatus()/diskStatus() convenience methods
- RefreshIndicator wired into a new minimal header row, driven by whether
  any of the six cache entries is refreshing
- RESEARCH assumption A3 settled: read all seven loader bodies; none
  consumes another's result — the concurrent fan-out is correct as-is
- Fixed a keepAliveLifecycle.test.ts assertion invalidated by the new 10s
  network-summary TTL (reactivation now also revalidates that resource,
  adding one more vpnStatus() call the test didn't previously account for)

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

neode-ui/src/api/rpc-client.ts

@@ -1021,6 +1021,7 @@ class RPCClient {
     return this.call({
       method: 'vpn.status',
       params: {},
+      dedup: true, // read-only status; safe to collapse concurrent callers (PERF-02)
     })
   }
 
@@ -1091,6 +1092,7 @@ class RPCClient {
     return this.call({
       method: 'network.dns-status',
       params: {},
+      dedup: true, // read-only status; safe to collapse concurrent callers (PERF-02)
     })
   }
 
@@ -1118,7 +1120,7 @@ class RPCClient {
     used_percent: number
     level: 'ok' | 'warning' | 'critical'
   }> {
-    return this.call({ method: 'system.disk-status' })
+    return this.call({ method: 'system.disk-status', dedup: true }) // read-only; safe to collapse concurrent callers (PERF-02)
   }
 
   async diskCleanup(): Promise<{