Fix Hermes plugin config: use config file instead of env vars

Hermes plugins don't inherit container env vars. Switch the Miniflux
plugin to read credentials from a config.json written by Ansible,
and drop requires_env / container env vars.

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

infra/hermes/docker-compose.yml

@@ -19,8 +19,6 @@ services:
       OPENROUTER_API_KEY: "${OPENROUTER_API_KEY}"
       TELEGRAM_BOT_TOKEN: "${TELEGRAM_BOT_TOKEN}"
       TELEGRAM_ALLOWED_USERS: "${TELEGRAM_ALLOWED_USERS}"
-      MINIFLUX_API_KEY: "${MINIFLUX_API_KEY}"
-      MINIFLUX_BASE_URL: "http://miniflux:8080"
     env_file:
       - .env