step 3: nodes repository + CRUD + CLI node commands

- types.go: TypeSpace/Case/Folder/Note/... + Slugify()
- node.go: Node struct, Meta, IsDeleted/IsRoot helpers
- repository.go: full CRUD (Create, Get, GetActive, ListChildren,
  ListRoots, UpdateTitle, Move, SoftDelete) + Meta KV (MetaSet,
  MetaGet, MetaList)
- node_cmd.go: thin wrappers around repository
- main.go: verstak node create/list/get/move/delete subcommands
- repository_test.go: 12 tests covering all CRUD paths

Acceptance: go build pass, go test pass (12 tests),
  CLI create+list+get+move+delete all working.

docs/PLAN.md

@@ -12,7 +12,7 @@
 | # | Шаг | Статус |
 |---|-----|--------|
 | 1 | Git init + Skeleton | ✅ выполнен |
-| 2 | Init + SQLite + First Migration | ⬜ не начат |
+| 2 | Init + SQLite + First Migration | ✅ выполнен |
 | 3 | Nodes Repository + CRUD + CLI Node | ⬜ не начат |
 | 4 | Vault Files: Trash + File Service + CLI File | ⬜ не начат |
 | 5 | Markdown Notes: Create/Read/Save + CLI Note | ⬜ не начат |