feat: v1.2.0-alpha — E2E encrypted mesh relay, steganography, relay status polling

Phase 5 mesh networking:
- E2E encrypted TX relay (X25519 + ChaCha20-Poly1305) — non-Archy nodes
  relay encrypted blobs transparently via Meshcore native routing
- Steganographic encoding modes (WeatherStation, SensorNetwork) — traffic
  looks like sensor data on the wire, 0xAA marker, configurable per-node
- Pre-flight Bitcoin Core health check on relay node — specific error codes
  (bitcoin_unreachable, bitcoin_syncing, tx_rejected) instead of generic fails
- mesh.relay-status RPC endpoint — frontend polls for relay result every 3s
- On-Chain / Lightning tabs in Off-Grid Bitcoin panel
- Archy Peers vs Mesh Broadcast relay mode selector
- Mesh view fills viewport (no page scroll), internal panel scrolling
- Version bump to 1.2.0-alpha

Also includes: deploy hardening, container fixes, IndeedHub updates,
boot screen, dashboard improvements, MASTER_PLAN task tracking

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

core/archipelago/src/api/rpc/mod.rs

@@ -655,11 +655,13 @@ impl RpcHandler {
             "mesh.rotate-prekeys" => self.handle_mesh_rotate_prekeys().await,
             // Phase 4: Off-grid Bitcoin operations
             "mesh.relay-tx" => self.handle_mesh_relay_tx(params).await,
+            "mesh.relay-status" => self.handle_mesh_relay_status(params).await,
             "mesh.block-headers" => self.handle_mesh_block_headers(params).await,
             "mesh.relay-lightning" => self.handle_mesh_relay_lightning(params).await,
             "mesh.deadman-status" => self.handle_mesh_deadman_status().await,
             "mesh.deadman-configure" => self.handle_mesh_deadman_configure(params).await,
             "mesh.deadman-checkin" => self.handle_mesh_deadman_checkin().await,
+            "mesh.test-send" => self.handle_mesh_test_send(params).await,
 
             // Transport layer (unified routing)
             "transport.status" => self.handle_transport_status().await,