Rename public discovery app from "finder" to "koja"

Rebrand the public café-discovery app: directories web/finder→web/koja and
docker/finder→docker/koja, plus all service wiring (docker-compose, Caddy
subdomain koja.meezi.ir, env vars KOJA_PORT / NEXT_PUBLIC_KOJA_URL, CI
workflows) and the app's display name (Koja / کجا).

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

docker-compose.caddy.yml

@@ -36,7 +36,7 @@ services:
       - api
       - web
       - website
-      - finder
+      - koja
       - admin-api
       - admin-web