feat: add CertFP authentication with SASL EXTERNAL

Per-network, per-nick client certificates (EC P-256, self-signed,
10-year validity) stored as combined PEM files. Authentication
cascade: SASL EXTERNAL > SASL PLAIN > NickServ IDENTIFY.

New commands: GENCERT, CERTFP, DELCERT. GENCERT auto-registers
the fingerprint with NickServ CERT ADD when the network is connected.

Includes email verification module for NickServ registration and
expanded NickServ interaction (IDENTIFY, REGISTER, VERIFY).

Containerfile

@@ -4,7 +4,10 @@ WORKDIR /app
 
 RUN pip install --no-cache-dir \
     "python-socks[asyncio]>=2.4" \
-    "aiosqlite>=0.19"
+    "aiosqlite>=0.19" \
+    "aiohttp>=3.9" \
+    "aiohttp-socks>=0.8" \
+    "cryptography>=41.0"
 
 ENV PYTHONUNBUFFERED=1
 ENV PYTHONDONTWRITEBYTECODE=1