feat(settings): per-service FIPS/Tor transport preference

Adds a user-configurable toggle for how each peer-to-peer service
reaches federated peers. Three options per service:

- Auto (default) — FIPS preferred, Tor fallback (current behavior).
- FIPS only — fail rather than fall through to Tor.
- Tor only — explicit opt-in to onion anonymity for that service.

Services covered (matching the UI rows):
- Federation — state sync, invites, peer notifications
- Peers — address/DID rotation broadcasts
- Peer Files — content catalog download/browse/preview
- Messaging — archipelago channel + mesh bridge
- Mesh File Sharing — content_ref blob fetches

Implementation:
- settings::transport — persisted struct + process-wide OnceLock handle
  (so deep call sites don't need data_dir threaded through signatures).
  On-disk file: <data_dir>/settings/transport_preferences.json; missing
  or corrupt → defaults (Auto everywhere).
- settings::transport::init() called from main.rs after config load.
- fips::dial::PeerRequest gains a .service(kind) builder; send_* checks
  the preference before choosing a transport. FIPS-only fails loudly
  when FIPS is unavailable (so users who pick it know when something
  falls back).
- Every FIPS-first migration site tags its PeerRequest with the
  matching PeerService so the toggle actually applies.
- transport.preferences + transport.set-preference RPCs added; wired
  into the dispatcher.
- neode-ui/src/views/settings/TransportPrefsCard.vue — standalone card
  with a 5-row Auto/FIPS/Tor tri-state. Not wired into Settings.vue —
  the user places components themselves (see feedback_ui_entry_points).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

core/archipelago/src/federation/invites.rs

@@ -232,6 +232,7 @@ async fn notify_join(
     });
 
     let _ = crate::fips::dial::PeerRequest::new(remote_fips_npub, remote_onion, "/rpc/v1")
+        .service(crate::settings::transport::PeerService::Federation)
         .timeout(std::time::Duration::from_secs(30))
         .send_json(&body)
         .await;

core/archipelago/src/federation/sync.rs

@@ -28,6 +28,7 @@ pub async fn sync_with_peer(
     });
 
     let (resp, transport) = PeerRequest::new(peer.fips_npub.as_deref(), &peer.onion, "/rpc/v1")
+        .service(crate::settings::transport::PeerService::Federation)
         .header("X-Federation-DID", local_did)
         .header("X-Federation-Sig", signature)
         .header("X-Federation-Timestamp", timestamp)
@@ -111,6 +112,7 @@ pub async fn deploy_to_peer(
     });
 
     let (resp, transport) = PeerRequest::new(peer.fips_npub.as_deref(), &peer.onion, "/rpc/v1")
+        .service(crate::settings::transport::PeerService::Federation)
         .header("X-Federation-DID", local_did)
         .header("X-Federation-Sig", signature)
         .header("X-Federation-Timestamp", timestamp)