fix: resolve ty no-matching-overload on Sandbox.kill() (#1119)

## Summary

- Fixes `ty` type checker reporting `error[no-matching-overload]` when
calling `Sandbox.kill()` (and all other methods using the
`class_method_variant` pattern)
- Single 2-line change: make `class_method_variant` inherit from
`Generic[T]` instead of `object`

## Problem

The `class_method_variant` descriptor uses `cast(T, self)` to tell type
checkers that the decorator preserves the original function's type.
Without `Generic[T]`, `T` is only a method-level TypeVar — `ty` doesn't
trust the cast and fails to resolve overloads at call sites. `mypy` and
`pyright` are more lenient and accept it either way.

Affected methods (both `Sandbox` and `AsyncSandbox`): `kill`, `connect`,
`set_timeout`, `get_info`, `get_metrics`, `beta_pause`.

## Fix

Adding `Generic[T]` makes `T` a class-level type parameter, so `ty` can
track the type binding through the descriptor
(`class_method_variant[(self, **opts) -> bool]`). The cast then makes
sense to all three type checkers.

## Verification

Tested with a consumer repro (`sandbox.kill()`) against:

| Type Checker | Before | After |
|---|---|---|
| ty 0.0.15 | `error[no-matching-overload]` | All checks passed |
| mypy 1.19.1 | All checks passed | All checks passed |
| pyright 1.1.408 | All checks passed | All checks passed |

## Test plan

- [x] Verified `ty check` passes on consumer-side repro
- [x] Verified `mypy` and `pyright` still pass (no regressions)
- [x] Verified Python syntax is valid
- [x] No runtime behavior change (`Generic[T]` only affects type-level
metadata)

Author: beran-t

.changeset/sparkly-comics-sin.md

@@ -0,0 +1,5 @@
+---
+'@e2b/python-sdk': patch
+---
+
+Fix type checker compatibility for class_method_variant descriptor

packages/python-sdk/e2b/sandbox/utils.py

@@ -1,10 +1,10 @@
-from typing import TypeVar, Any, cast, Optional, Type
+from typing import TypeVar, Any, Generic, cast, Optional, Type
 import functools
 
 T = TypeVar("T")
 
 
-class class_method_variant(object):
+class class_method_variant(Generic[T]):
     def __init__(self, class_method_name):
         self.class_method_name = class_method_name