feat: initial Jimi Gallery prototype

- Public site (Home/Artists/Exhibitions/News/About/Contact) with EN/KO/JA i18n
- Admin panel with login, CRUD, image upload, multilingual editing
- Exhibition slider/lightbox view
- FastAPI + MongoDB backend, JWT auth
- Docker Compose deployment, behind nginx at jimi.yakenator.io

.dockerignore

@@ -0,0 +1,7 @@
+**/__pycache__
+**/.pytest_cache
+**/*.pyc
+.git
+.gitignore
+node_modules
+.DS_Store