refactor: implement template-driven node tree and human-readable vault layout

Unified Node model: added template_id, fs_path, archived, sort_order fields.
Template registry: system templates embedded as JSON (folder/project/client/
document/recipe), with Registry for enabled/disabled/filtered access.
SafeDisplayNameToPathSegment: human-readable path segments with Cyrillic
support, illegal char replacement, uniqueness via numeric suffixes.
Sidebar refactored: system views (Today/Inbox/Activity) separate from
workspace tree. Creation menu built dynamically from enabled templates.
Create/Rename/Move: physical folder operations with fs_path update,
recursive descendant path updates.
DB migration 012: adds template_id, fs_path, archived columns.
Vault migration command: rebuilds fs_path for existing nodes.
Tests: safename, registry, node model, repository integration.
Docs: VAULT_LAYOUT.md, TEMPLATES.md, PLAN.md updated.
i18n: nav.system, nav.workspace, template.*, common.rename/archive,
migrate.* keys added to ru.json and en.json.

internal/i18n/locales/en.json

@@ -102,5 +102,25 @@
   "server.emailConfirmSubject": "Confirm your Verstak Sync account",
   "server.emailConfirmBody": "Welcome to Verstak Sync!\n\nPlease confirm your email by clicking:\n%s\n\nIf you did not register, ignore this message.",
   "server.emailResetSubject": "Verstak Sync password reset",
-  "server.emailResetBody": "Reset your Verstak Sync password:\n\n%s\n\nThis link expires in 1 hour."
+  "server.emailResetBody": "Reset your Verstak Sync password:\n\n%s\n\nThis link expires in 1 hour.",
+
+  "nav.system": "System",
+  "nav.workspace": "Workspace",
+  "nav.noNodes": "No nodes",
+  "nav.openFolder": "Open folder",
+  "nav.createInside": "Create inside",
+
+  "template.folder": "Folder",
+  "template.project": "Project",
+  "template.client": "Client",
+  "template.document": "Document",
+  "template.recipe": "Recipe",
+
+  "common.archive": "Archive",
+
+  "migrate.dryRun": "Dry run",
+  "migrate.foldersCreated": "Folders created",
+  "migrate.templatesSet": "Templates set",
+  "migrate.errors": "Errors",
+  "migrate.noNodes": "No nodes to migrate"
 }

internal/i18n/locales/ru.json

@@ -384,5 +384,25 @@
   "server.emailConfirmSubject": "Подтверждение аккаунта Verstak Sync",
   "server.emailConfirmBody": "Добро пожаловать в Verstak Sync!\n\nПодтвердите email, перейдя по ссылке:\n%s\n\nЕсли вы не регистрировались, проигнорируйте это письмо.",
   "server.emailResetSubject": "Сброс пароля Verstak Sync",
-  "server.emailResetBody": "Сброс пароля Verstak Sync:\n\n%s\n\nСсылка действительна 1 час."
+  "server.emailResetBody": "Сброс пароля Verstak Sync:\n\n%s\n\nСсылка действительна 1 час.",
+
+  "nav.system": "Системное",
+  "nav.workspace": "Рабочее пространство",
+  "nav.noNodes": "Нет узлов",
+  "nav.openFolder": "Открыть папку",
+  "nav.createInside": "Создать внутри",
+
+  "template.folder": "Папка",
+  "template.project": "Проект",
+  "template.client": "Клиент",
+  "template.document": "Документ",
+  "template.recipe": "Рецепт",
+
+  "common.archive": "Архивировать",
+
+  "migrate.dryRun": "Пробный запуск",
+  "migrate.foldersCreated": "Папок создано",
+  "migrate.templatesSet": "Шаблонов назначено",
+  "migrate.errors": "Ошибки",
+  "migrate.noNodes": "Нет узлов для миграции"
 }