feat: host-derived nicks and generic identity

Nick is now deterministically generated from the exit endpoint
hostname via seeded markov chain. Same exit IP always produces the
same nick. Config nick field is optional fallback only.

Registration uses generic ident (user/ident) and realname
(realname/unknown) instead of random markov words.

Also fixes compose env vars and build target to use podman-compose.

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

config/bouncer.example.toml

@@ -13,13 +13,15 @@ port = 1080
 
 # Registration uses a random nick and generic ident/realname.
 # After surviving the probation window (no k-line), the bouncer
-# switches to your configured nick and joins channels.
+# derives a stable nick from the exit endpoint hostname. The same
+# exit IP always produces the same nick across reconnects.
+# Set nick to override (optional, used as fallback only).
 
 [networks.libera]
 host = "irc.libera.chat"
 port = 6697
 tls = true
-nick = "mynick"
+# nick = "mynick"       # optional: override host-derived nick
 channels = ["#test"]
 autojoin = true
 
@@ -27,5 +29,4 @@ autojoin = true
 # host = "irc.oftc.net"
 # port = 6697
 # tls = true
-# nick = "mynick"
 # channels = ["#debian"]