Switch continuwuity env vars to CONTINUWUITY_ prefix

The CONDUWUIT_ prefix still works in v26.6.1, but is a legacy
compatibility name from before the conduwuit -> continuwuity rebrand.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

etc/services/continuwuity/compose.yml

@@ -7,8 +7,8 @@ services:
       - ALL
     read_only: true
     environment:
-      CONDUWUIT_CONFIG: /etc/continuwuity/continuwuity.toml
-      CONDUWUIT_DATABASE_PATH: /var/lib/continuwuity
+      CONTINUWUITY_CONFIG: /etc/continuwuity/continuwuity.toml
+      CONTINUWUITY_DATABASE_PATH: /var/lib/continuwuity
     ports:
       - "${SERVICE_CONTINUWUITY_BIND_PORT_CLIENT_API}:6167"
     volumes: