fix(deploy): automatic addresses on the edge network from its upper half

The deploy that brought the edge network failed and left learn.halkyon.eu
down: the server, started before Caddy, got the first free address on
the network, 172.30.80.2, which is Caddy's fixed one, so Caddy couldn't
start ("Address already in use"). Containers without an address of their
own now get one from 172.30.80.128/25, below which the fixed ones (Caddy
.2, sidecars from .10) are never taken.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

deploy/compose.yaml

@@ -137,6 +137,12 @@ networks:
     ipam:
       config:
         - subnet: 172.30.80.0/24
+          gateway: 172.30.80.1
+          # Containers without an address of their own (the server) get one from the
+          # upper half, so the fixed ones below it (Caddy .2, sidecars from .10) are
+          # never taken: the server started first once and took Caddy's (2026-10-14).
+          # (With a range alone, Docker would move the gateway to its first address.)
+          ip_range: 172.30.80.128/25
 
 volumes:
   caddy_data: