Add configuration revisions system and project variant deletion

Features:
- Configuration versioning: immutable snapshots in local_configuration_versions
- Revisions UI: /configs/:uuid/revisions page to view version history
- Clone from version: ability to clone configuration from specific revision
- Project variant deletion: DELETE /api/projects/:uuid endpoint
- Updated CLAUDE.md with new architecture details and endpoints

Architecture updates:
- local_configuration_versions table for immutable snapshots
- Version tracking on each configuration save
- Rollback capability to previous versions
- Variant deletion with main variant protection

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -20,6 +20,7 @@
 - Local-first: чтение и запись происходят в SQLite
 - MariaDB используется как сервер синхронизации
 - Background worker: периодический sync push+pull
+- Система ревизий конфигураций: immutable snapshots при каждом сохранении (local_configuration_versions)
 
 ## Guardrails
 - Не возвращать в проект удалённые legacy-разделы: cron jobs, importer utility, admin pricing, alerts, stock import.
@@ -32,6 +33,7 @@
 - `local_components`
 - `local_pricelists`, `local_pricelist_items`
 - `local_configurations`
+- `local_configuration_versions` — immutable snapshots (ревизии) при каждом сохранении
 - `local_projects`
 - `pending_changes`
 
@@ -42,14 +44,15 @@
 | Components | `GET /api/components`, `GET /api/components/:lot_name`, `GET /api/categories` |
 | Quote | `POST /api/quote/validate`, `POST /api/quote/calculate`, `POST /api/quote/price-levels` |
 | Pricelists (read-only) | `GET /api/pricelists`, `GET /api/pricelists/latest`, `GET /api/pricelists/:id`, `GET /api/pricelists/:id/items`, `GET /api/pricelists/:id/lots` |
-| Configs | CRUD + refresh/clone/reactivate/rename/project binding via `/api/configs/*` |
-| Projects | CRUD + nested configs via `/api/projects/*` |
+| Configs | CRUD + refresh/clone/reactivate/rename/project binding + versions/rollback via `/api/configs/*` |
+| Projects | CRUD + nested configs + `DELETE /api/projects/:uuid` (delete variant) via `/api/projects/*` |
 | Sync | `GET /api/sync/status`, `GET /api/sync/readiness`, `GET /api/sync/info`, `GET /api/sync/users-status`, `POST /api/sync/components`, `POST /api/sync/pricelists`, `POST /api/sync/all`, `POST /api/sync/push`, `GET /api/sync/pending`, `GET /api/sync/pending/count` |
 | Export | `POST /api/export/csv` |
 
 ## Web Routes
 - `/configs`
 - `/configurator`
+- `/configs/:uuid/revisions`
 - `/projects`
 - `/projects/:uuid`
 - `/pricelists`