docs: document Tor control port integration

Adds Tor control port section to USAGE.md covering config,
auth modes, rate limiting, and API endpoints. Updates README
feature line and config example, CHEATSHEET with tor snippets,
and marks the feature complete in TASKS.md and ROADMAP.md.

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

docs/CHEATSHEET.md

@@ -59,6 +59,20 @@ proxy_pool:
   report_url: ""     # POST dead proxies (optional)
 ```
 
+## Tor Control Port (config)
+
+```yaml
+tor:
+  control_port: 9051
+  password: ""               # or cookie_file: /path/to/cookie
+  newnym_interval: 60        # auto-rotate every 60s (0 = manual)
+```
+
+```bash
+curl -s http://127.0.0.1:1081/tor | jq .                  # status
+curl -s -X POST http://127.0.0.1:1081/tor/newnym | jq .   # new circuit
+```
+
 ## Hot Reload
 
 ```bash