v5.6.0 Tor-native: embed Tor, force .onion-only networking

Every Triangles wallet is now a Tor node. Staking rewards subsidize
Tor infrastructure.

Core changes:
- Embedded Tor 0.4.9.6 as git submodule
- ConnectNode rejects all non-.onion peers
- Tor failure is fatal - wallet requires Tor to operate
- All proxies forced through embedded Tor SOCKS
- Clearnet (IPv4/IPv6) disabled at startup
- HTTP seed fetch routes through Tor proxy (removed boost::asio dep)
- Merged PoW cleanup: -623 lines of dead mining code
- Stripped dead LEGACY/MIXED bootstrap modes from net_bootstrap
- RPC getnetworkinfo reports tor_native mode

Tooling:
- scripts/bump-version.sh syncs version across all 17+ files
- Version bumped to 5.6.0 across all packaging manifests

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packaging/docker/docker-compose.yml

@@ -3,7 +3,7 @@ version: "3.8"
 services:
   trianglesd:
     build: .
-    image: cryptographic-triangles/trianglesd:5.3.7
+    image: cryptographic-triangles/trianglesd:5.6.0
     container_name: trianglesd
     restart: unless-stopped
     ports: