feat: initial IRC bouncer implementation

Async Python IRC bouncer with SOCKS5 proxy support, multi-network
connections, password auth, and persistent SQLite backlog with replay.

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

docs/DEBUG.md

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+# Debugging
+
+## Verbose Mode
+
+```bash
+bouncer -c config/bouncer.toml -v
+```
+
+Debug logging shows:
+- SOCKS5 proxy connection attempts
+- IRC server registration
+- Client connect/disconnect events
+- Message routing
+- Backlog replay counts
+
+## Common Issues
+
+### "config not found"
+
+Ensure the config path is correct:
+
+```bash
+bouncer -c /full/path/to/bouncer.toml
+```
+
+### Connection refused (SOCKS5 proxy)
+
+Verify the proxy is running:
+
+```bash
+ss -tlnp | grep 1080
+```
+
+### Connection timeout to IRC server
+
+Check the SOCKS5 proxy can reach the IRC server:
+
+```bash
+curl --socks5 127.0.0.1:1080 -v telnet://irc.libera.chat:6697
+```
+
+### Nick already in use
+
+The bouncer appends `_` to the nick and retries. Check logs for:
+
+```
+WARNING bouncer.network [libera] nick in use, trying mynick_
+```
+
+### TLS certificate errors
+
+If connecting to a server with a self-signed cert, this is currently not supported. All TLS connections use the system CA store.
+
+## Inspecting the Backlog Database
+
+```bash
+sqlite3 config/bouncer.db
+
+-- Recent messages
+SELECT * FROM messages ORDER BY id DESC LIMIT 20;
+
+-- Messages per network
+SELECT network, COUNT(*) FROM messages GROUP BY network;
+
+-- Client state
+SELECT * FROM client_state;
+```
+
+## Log Format
+
+```
+HH:MM:SS LEVEL module message
+```
+
+Levels: `DEBUG`, `INFO`, `WARNING`, `ERROR`