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>

Caddyfile

@@ -6,7 +6,7 @@
 # Caddy auto-provisions Let's Encrypt TLS — no certbot needed.
 # Domains needed in DNS (all → same server IP):
 #   meezi.ir, app.meezi.ir, api.meezi.ir,
-#   finder.meezi.ir, admin.meezi.ir, admin-api.meezi.ir
+#   koja.meezi.ir, admin.meezi.ir, admin-api.meezi.ir
 
 {
     email {$ACME_EMAIL}
@@ -27,9 +27,9 @@ api.{$DOMAIN} {
     reverse_proxy api:8080
 }
 
-# ── Finder (public discovery) ────────────────────────────────────────────────
-finder.{$DOMAIN} {
-    reverse_proxy finder:3000
+# ── Koja (public discovery) ──────────────────────────────────────────────────
+koja.{$DOMAIN} {
+    reverse_proxy koja:3000
 }
 
 # ── Super-Admin panel ────────────────────────────────────────────────────────