fix(host): correct host workspace cleanup on Windows (#883)

## Summary
- Fix host-mode cleanup to remove the job **workspace** directory after a run (instead of leaving checkouts behind).
- On Windows, track step process PIDs and terminate remaining process trees during teardown before attempting workspace deletion (prevents file-lock failures).
- Skip workspace deletion when `bind_workdir` is enabled to avoid conflicting with runner-level task directory cleanup.

## Implementation details
- `HostEnvironment` now records PIDs for started commands and best-effort terminates them on Windows during `Remove()`.
- Workspace removal uses a small retry loop on Windows to handle transient locks.
- `BindWorkdir` is propagated into `HostEnvironment` so cleanup behavior matches runner configuration.

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: silverwind <2021+silverwind@noreply.gitea.com>
Reviewed-on: https://gitea.com/gitea/runner/pulls/883
Reviewed-by: silverwind <2021+silverwind@noreply.gitea.com>

act/runner/run_context.go

@@ -220,11 +220,12 @@ func (rc *RunContext) startHostEnvironment() common.Executor {
 		}
 		toolCache := filepath.Join(cacheDir, "tool_cache")
 		rc.JobContainer = &container.HostEnvironment{
-			Path:      path,
-			TmpDir:    runnerTmp,
-			ToolCache: toolCache,
-			Workdir:   rc.Config.Workdir,
-			ActPath:   actPath,
+			Path:        path,
+			TmpDir:      runnerTmp,
+			ToolCache:   toolCache,
+			Workdir:     rc.Config.Workdir,
+			BindWorkdir: rc.Config.BindWorkdir,
+			ActPath:     actPath,
 			CleanUp: func() {
 				os.RemoveAll(miscpath)
 			},