feat(content): owned-content persistence + Fedimint paid downloads, fmcd caps fix, FIPS warm-path perf

Buyer-side paid downloads now persist: purchases are cached on disk
(content_owned.rs) keyed by (seller onion, content_id), the gallery shows
an "Owned" badge unblurred, and items view/play in-app from the local
cache with no re-payment or reliance on a browser download (which
silently failed on the mobile companion). New RPCs content.owned-list /
content.owned-get. Validated e2e .116<-.198 (paid 100 sats via Fedimint,
166KB jpeg returns, survives restart).

fedimint-clientd manifest: restore the standard container capability set
(CHOWN/DAC_OVERRIDE/FOWNER/SETUID/SETGID) so fmcd's startup chown of an
existing-federation /data succeeds instead of dying EPERM (#7). Confirmed
the orchestrator applies these to the running container.

FIPS perf: tighten the supervisor warm-path keepalive 45s -> 25s so peer
paths stay inside the ~30-60s NAT cold window. Dials now reliably land on
FIPS instead of re-punching and falling back to Tor. Measured to the same
peer: cloud browse 18-22s -> 0.4s; full Fedimint paid download 29s -> 11s
(residual is the seller-side guardian reissue round-trip).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

neode-ui/src/views/web5/Web5.vue

@@ -329,7 +329,7 @@ async function loadEcashBalance() {
     const res = await rpcClient.call<{ balance_sats: number; token_count: number }>({ method: 'wallet.ecash-balance' })
     ecashBalance.value = res.balance_sats ?? 0
   } catch {
-    ecashBalance.value = 0
+    // Keep last-known balance on a transient failure rather than flashing 0.
   }
 }