feat(vm-ops): make reinstall/clone/change-password async via DeployTask

Backend:
- Add DeployTask.kind column ('deploy'|'reinstall'|'clone'|'change_password')
  + Migration 23: ALTER TABLE deploy_tasks ADD kind, drop NOT NULL on template_id
- Update DeployTask.to_dict() with kind-aware Russian descriptions
- New backend/app/api/proxmox/async_ops.py with three workers:
    _do_reinstall_sync, _do_clone_sync, _do_change_password_sync
  All run on shared _deploy_executor thread pool from templates.py and
  report progress through _update_deploy_task (DB + WebSocket broadcast)
- Rewrite five vms.py endpoints to return 202 + DeployTaskStartResponse:
    POST /vm/{vmid}/clone, /container/{vmid}/clone,
    POST /vm/{vmid}/reinstall,
    POST /vm/{vmid}/change-password, /container/{vmid}/change-password

Frontend:
- DeployTask: add 'kind' and 'server_id' fields
- useCloneInstance/useReinstallInstance/useChangePassword now return
  AsyncTaskResponse {task_id, status, name}; remove invalidateQueries
- InstanceActionDialogs: each onSuccess pushes task to deploy-tasks-store
  with appropriate kind, shows 'launched in background' toast
- InstancesPage:
  * ghostRows only for kind in {deploy, clone}, deduped by (server_id, vmid)
  * reinstall / change_password tasks shown as inline overlay (badge + ring)
    on the existing VM row's status column

backend/migrations/migrations.py

@@ -1287,6 +1287,31 @@ def migrate_deploy_tasks(conn):
     logger.info("✓ deploy_tasks table created")
 
 
+def migrate_deploy_tasks_kind(conn):
+    """Migration 23: Add 'kind' column to deploy_tasks (deploy/reinstall/clone/change_password)"""
+    # Check if column exists
+    result = conn.execute(text("""
+        SELECT column_name FROM information_schema.columns
+        WHERE table_name = 'deploy_tasks' AND column_name = 'kind'
+    """))
+    if result.fetchone():
+        logger.info("✓ deploy_tasks.kind already exists")
+        return
+    conn.execute(text("""
+        ALTER TABLE deploy_tasks
+        ADD COLUMN kind VARCHAR(30) NOT NULL DEFAULT 'deploy'
+    """))
+    conn.execute(text("""
+        CREATE INDEX IF NOT EXISTS idx_deploy_tasks_kind
+        ON deploy_tasks (kind)
+    """))
+    # template_id may be NULL for non-deploy tasks (clone/reinstall don't always need it)
+    conn.execute(text("""
+        ALTER TABLE deploy_tasks ALTER COLUMN template_id DROP NOT NULL
+    """))
+    logger.info("✓ deploy_tasks.kind column added")
+
+
 def run_all_migrations(engine, db_session=None):
     """
     Run all migrations in order.
@@ -1477,6 +1502,14 @@ def run_all_migrations(engine, db_session=None):
                 logger.warning(f"Deploy tasks migration: {e}")
                 conn.rollback()
 
+            # Migration 23: deploy_tasks.kind column
+            try:
+                migrate_deploy_tasks_kind(conn)
+                conn.commit()
+            except Exception as e:
+                logger.warning(f"Deploy tasks kind migration: {e}")
+                conn.rollback()
+
         logger.info("=" * 50)
         logger.info("✓ All migrations completed successfully")
         logger.info("=" * 50)