Add initial framework of configuration.

feat: configuration file system of app.

Note: still work in progress.

docs/roadmap.md

@@ -1,24 +1,37 @@
 # Roadmap
 
-See `README.md` for high-level feature list. This file tracks detailed progress.
-
 ## v0
 
 | Feature | Status | Notes |
 |---------|--------|-------|
-| CLI config management | ⬜ planned | |
-| JWT authentication | ⬜ planned | |
-| File upload/download/manage APIs | ⬜ planned | |
-| Admin endpoints | ⬜ planned | |
-| WebDAV | ⬜ planned | |
+| CLI config management | ⬜ plan | |
+| JWT authentication | ⬜ plan | access + refresh tokens, refresh token in DB |
+| File upload/download/manage APIs | ⬜ plan | REST API via Gin |
+| Admin endpoints | ⬜ plan | user CRUD for superusers |
+| WebDAV | ⬜ plan | future v0 or v1 |
+
+## Implementation Tasks
+
+Package-level implementation order (each task includes unit tests):
+
+1. `internal/config` — Viper loader, config struct
+2. `internal/model` — domain types, error codes
+3. `internal/api` — JSON response helpers
+4. `internal/auth` — JWT utils
+5. `internal/storage` — backend interface + local fs
+6. `internal/repository` — interfaces + GORM/SQLite impl
+7. `internal/service` — auth, file, admin services
+8. `internal/middleware` — requestid, logger, cors, auth
+9. `internal/handler` — auth, file, admin handlers
+10. `internal/server` — Gin wiring, route registration
+11. `cmd/serve.go`, `cmd/config.go`, `cmd/status.go`
+12. Integration tests
 
 ## Future
 
 | Feature | Status | Notes |
 |---------|--------|-------|
-| Image server | ⬜ planned | |
-| Pastebin & code snippets | ⬜ planned | |
-| S3 storage backend | ⬜ planned | |
-| Nextcloud-compatible API | ⬜ planned | |
-
-Update status after completing related work.
+| Image server | ⬜ plan | thumbnail generation |
+| Pastebin & code snippets | ⬜ plan | in sharing context |
+| S3 storage backend | ⬜ plan | new storage impl |
+| Nextcloud-compatible API | ⬜ plan | new handler layer on existing services |