_internal(fix[async_subprocess]): Fix mypy type errors and formatting

why: Ensure Phase 1 passes full verification pipeline
what:
- Add None checks before .strip() calls on result.stdout in tests
- Apply ruff formatting to list comprehension in _args_as_list()

Author: tony

src/libvcs/_internal/async_subprocess.py

@@ -141,7 +141,9 @@ def _args_as_list(self) -> list[str]:
             # Single command (str, bytes, or PathLike)
             return [str(args) if not isinstance(args, bytes) else args.decode()]
         # At this point, args is Sequence[StrOrBytesPath]
-        return [str(arg) if not isinstance(arg, bytes) else arg.decode() for arg in args]
+        return [
+            str(arg) if not isinstance(arg, bytes) else arg.decode() for arg in args
+        ]
 
     async def _create_process(
         self,

tests/_internal/test_async_subprocess.py

@@ -187,6 +187,7 @@ async def test_run_with_cwd(self, tmp_path: Path) -> None:
         cmd = AsyncSubprocessCommand(args=["pwd"], cwd=tmp_path)
         result = await cmd.run(text=True)
 
+        assert result.stdout is not None
         assert result.stdout.strip() == str(tmp_path)
 
     @pytest.mark.asyncio
@@ -222,16 +223,12 @@ async def test_wait_with_timeout(self) -> None:
     @pytest.mark.asyncio
     async def test_concurrent_commands(self) -> None:
         """Test running multiple commands concurrently."""
-        commands = [
-            AsyncSubprocessCommand(args=["echo", str(i)])
-            for i in range(5)
-        ]
+        commands = [AsyncSubprocessCommand(args=["echo", str(i)]) for i in range(5)]
 
-        results = await asyncio.gather(
-            *[cmd.run(text=True) for cmd in commands]
-        )
+        results = await asyncio.gather(*[cmd.run(text=True) for cmd in commands])
 
         assert len(results) == 5
         for i, result in enumerate(results):
+            assert result.stdout is not None
             assert result.stdout.strip() == str(i)
             assert result.returncode == 0