feat: add bouncer control commands via /msg *bouncer

Users can now inspect bouncer state and manage it from their IRC client
by sending PRIVMSG to *bouncer (or bouncer). Supported commands:
HELP, STATUS, INFO, UPTIME, NETWORKS, CREDS. Responses arrive as
NOTICE messages. All commands are case-insensitive.

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

docs/CHEATSHEET.md

@@ -41,6 +41,18 @@ make clean      # rm .venv, build artifacts
 PASS <password>                 # authenticate (all networks)
 ```
 
+## Bouncer Commands
+
+```
+/msg *bouncer HELP                  # list commands
+/msg *bouncer STATUS                # all network states
+/msg *bouncer INFO libera           # detailed network info
+/msg *bouncer UPTIME                # process uptime
+/msg *bouncer NETWORKS              # list networks
+/msg *bouncer CREDS                 # all NickServ creds
+/msg *bouncer CREDS libera          # creds for one network
+```
+
 ## Namespacing
 
 ```
@@ -124,6 +136,7 @@ src/bouncer/
   proxy.py       # SOCKS5 connector (local DNS, multi-IP)
   network.py     # server connection + state machine
   client.py      # client session handler
+  commands.py    # bouncer control commands (/msg *bouncer)
   router.py      # message routing + backlog trigger
   server.py      # TCP listener
   backlog.py     # SQLite store/replay/prune