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/mesh/ratchet.rs

@@ -440,7 +440,7 @@ mod tests {
                 prev_chain_n: 0,
                 message_n: 0,
             },
-            ciphertext: vec![0x01, 0x02, 0x03; 30].into_iter().flatten().collect(),
+            ciphertext: vec![[0x01, 0x02, 0x03]; 30].into_iter().flatten().collect(),
         };
         let bytes = msg.to_bytes();
         let parsed = RatchetMessage::from_bytes(&bytes).unwrap();