feat: move SaaS app to /platform base path, Logto becomes catch-all

Eliminates all Logto path enumeration in Traefik. Routing is now:
- /platform/* → cameleer-saas (SPA + API)
- /server/* → server-ui
- /* (catch-all) → Logto (sign-in, OIDC, assets, everything)

Spring context-path handles backend prefix transparently. No changes
needed in controllers, SecurityConfig, or interceptors.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker/logto-bootstrap.sh

@@ -43,8 +43,8 @@ SERVER_UI_PASS="${SERVER_UI_PASS:-admin}"
 # Redirect URIs (derived from PUBLIC_HOST and PUBLIC_PROTOCOL)
 HOST="${PUBLIC_HOST:-localhost}"
 PROTO="${PUBLIC_PROTOCOL:-https}"
-SPA_REDIRECT_URIS="[\"${PROTO}://${HOST}/callback\"]"
-SPA_POST_LOGOUT_URIS="[\"${PROTO}://${HOST}/login\"]"
+SPA_REDIRECT_URIS="[\"${PROTO}://${HOST}/platform/callback\"]"
+SPA_POST_LOGOUT_URIS="[\"${PROTO}://${HOST}/platform/login\"]"
 TRAD_REDIRECT_URIS="[\"http://${HOST}:8081/oidc/callback\"]"
 TRAD_POST_LOGOUT_URIS="[\"http://${HOST}:8081\"]"