Implement balance monitoring and notification for Selectel API integration

- Added support for balance tracking using `SELECTEL_API_TOKEN` in the configuration.
- Introduced new balance notification logic in the local watchdog, alerting users on balance changes based on defined thresholds.
- Updated documentation to include instructions for setting up balance notifications and the required environment variables.
- Enhanced the `ready` and `session` modules to initialize balance state and handle notifications during GPU operations.
- Refactored the CLI and related components to support the new balance monitoring features, ensuring a seamless user experience.

src/gpu_rent/session.py

@@ -22,7 +22,7 @@ from gpu_rent.cloud import (
 )
 from gpu_rent.bootstrap import run_bootstrap
 from gpu_rent.provision import provision_vm, tune_swarm_perf
-from gpu_rent.ready import wait_backend_idle
+from gpu_rent.ready import verify_stack_on_vm, wait_backend_idle
 from gpu_rent.snapshot import ensure_boot_snapshot
 from gpu_rent.notify import notify_ready
 from gpu_rent.config import Config
@@ -127,6 +127,19 @@ def _bind_access(
             log(f"perf tune: {exc}")
     else:
         log("ready: llm-only (без ожидания SwarmUI Idle)")
+
+    try:
+        checks = verify_stack_on_vm(cfg, ip, log, timeout=300.0)
+        state.notes = dict(state.notes or {})
+        state.notes["stack_vm"] = [
+            {"name": c.name, "ok": c.ok, "detail": c.detail} for c in checks
+        ]
+    except CloudError as exc:
+        state.notes = dict(state.notes or {})
+        state.notes["stack_vm_error"] = str(exc)[:500]
+        save_state(state)
+        raise
+
     try:
         ensure_boot_snapshot(
             conn,
@@ -137,6 +150,27 @@ def _bind_access(
     except CloudError as exc:
         log(f"snapshot: {exc}")
     notify_ready(cfg, log)
+    try:
+        from gpu_rent.balance import (
+            BalanceWatchState,
+            fetch_balance_rub,
+            save_balance_state,
+        )
+
+        if cfg.selectel_api_token:
+            rub = fetch_balance_rub(cfg.selectel_api_token)
+            save_balance_state(
+                BalanceWatchState(baseline_rub=rub, last_balance_rub=rub)
+            )
+            log(
+                f"balance: baseline {rub:.0f} ₽ "
+                f"(уведомление каждые {cfg.balance_notify_step_rub:.0f} ₽, "
+                "нужен local-watchdog)"
+            )
+        else:
+            log("balance: SELECTEL_API_TOKEN не задан — шаги по ₽ skip")
+    except Exception as exc:
+        log(f"balance baseline: {exc}")
     state.bootstrapped = True
     state.phase = "ready_cloud"
     state.notes = dict(state.notes or {})
@@ -464,5 +498,11 @@ def cmd_stop(
             clear_lease()
         except Exception:
             pass
+        try:
+            from gpu_rent.balance import clear_balance_state
+
+            clear_balance_state()
+        except Exception:
+            pass
         log("фаза idle" + ("" if destroy_disks else " (диски на месте)"))
         return state