feat: multi-Tor round-robin via tor_nodes config

New top-level tor_nodes list distributes traffic across multiple Tor
SOCKS proxies. First hop is replaced at connection time by round-robin
selection; health tests also rotate across all nodes. FirstHopPools
are created for each node when pool_size > 0.

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

docs/CHEATSHEET.md

@@ -56,6 +56,16 @@ listeners:
       - socks5://127.0.0.1:9050             # Tor only
 ```
 
+## Multi-Tor Round-Robin (config)
+
+```yaml
+tor_nodes:                              # overrides first hop in all listeners
+  - socks5://10.200.1.1:9050
+  - socks5://10.200.1.254:9050
+  - socks5://10.200.1.250:9050
+  - socks5://10.200.1.13:9050
+```
+
 ## Performance Tuning (config)
 
 ```yaml