fix(docker): re-add RUNTIME_API_ORIGIN passthrough so .env value reaches the container

The previous commit dropped the line under the assumption that Docker Compose
would auto-forward variables from .env to the container. It does not -- .env
only feeds substitution in the compose file itself; containers receive only
what is listed under `environment:` (or via `env_file:`). Removing the
passthrough made RUNTIME_API_ORIGIN inoperative for Docker self-hosting:
users could set it in .env but the webapp container never saw the value, so
runners kept resolving TRIGGER_API_URL from API_ORIGIN/APP_ORIGIN.

Restoring the passthrough is now safe because the zod schema for
RUNTIME_API_ORIGIN normalizes empty strings to undefined, so the unset path
( -> '') no longer short-circuits the '??' fallback
chain. This is the defense-in-depth combination originally suggested in
review: passthrough at the compose layer + empty-string normalization at the
schema layer.

Author: ThullyoCunha

hosting/docker/webapp/docker-compose.yml

@@ -43,6 +43,7 @@ services:
       APP_ORIGIN: ${APP_ORIGIN:-http://localhost:8030}
       LOGIN_ORIGIN: ${LOGIN_ORIGIN:-http://localhost:8030}
       API_ORIGIN: ${API_ORIGIN:-http://localhost:8030}
+      RUNTIME_API_ORIGIN: ${RUNTIME_API_ORIGIN:-}
       ELECTRIC_ORIGIN: http://electric:3000
       DATABASE_URL: ${DATABASE_URL:-postgresql://postgres:postgres@postgres:5432/main?schema=public&sslmode=disable}
       DIRECT_URL: ${DIRECT_URL:-postgresql://postgres:postgres@postgres:5432/main?schema=public&sslmode=disable}