Prevent and recover from wedged Wine-hosted processes

Prompted by a real incident: an MSBuild node-reuse worker (its own
/nodeReuse:true default) survived a build getting interrupted, came
back deadlocked, and got reused by the next `msbuild` invocation -
which then failed with a confusing, unrelated-looking
`System.TypeLoadException` on Microsoft.VisualStudio.Telemetry on
every call for hours, until the stale process was killed by hand.
That's exactly the "unrelated blocker" noted in this repo's own
earlier session notes (CLAUDE.md) while debugging a real project's
build - it wasn't a missing dependency, it was a corrupted reused
process.

Two changes:

- vintner now forces /nodeReuse:false on every msbuild invocation
  (unless the caller already passed their own /nodeReuse or /nr
  switch), so a wedged worker can never poison a later, unrelated
  build in the first place. Costs each invocation the couple-hundred-
  ms/node startup time node reuse exists to save.

- VINTNER_TIMEOUT (a duration string, e.g. "30m") bounds how long any
  single tool invocation is allowed to run, for the case something
  wedges that isn't MSBuild-specific. Every exec.Command site in
  internal/wrapper now goes through a shared newToolCommand
  constructor that, when the timeout is set, kills the *whole*
  process group (not just the immediate `wine` process - a wedged
  child surviving under it is exactly the scenario this needs to
  reach) via a context deadline, and reports a clear "timed out after
  Xm" message (exit 124, matching the timeout(1) convention) instead
  of a bare "signal: killed". Unset by default - every real build
  observed stays unbounded, matching Windows' own behavior.

Verified end-to-end, not just at the unit level: a real `sleep 30`
through the `cmd` native wrapper with VINTNER_TIMEOUT=1s was killed
within the deadline and reported the timeout clearly (exit 124); a
real `cl` invocation with the same 1s timeout finished normally
(0.26s) without being mistaken for a hang.

internal/wrapper/native.go

@@ -1,6 +1,7 @@
 package wrapper
 
 import (
+	"fmt"
 	"os"
 	"os/exec"
 )
@@ -25,17 +26,21 @@ func execInherit(args []string) int {
 	if len(args) == 0 {
 		return 0
 	}
-	cmd := exec.Command(args[0], args[1:]...)
-	cmd.Stdin = os.Stdin
-	cmd.Stdout = os.Stdout
-	cmd.Stderr = os.Stderr
-	setNewProcessGroup(cmd)
-	if err := cmd.Start(); err != nil {
+	tc, cleanup := newToolCommand(args[0], args[1:]...)
+	defer cleanup()
+	tc.Stdin = os.Stdin
+	tc.Stdout = os.Stdout
+	tc.Stderr = os.Stderr
+	if err := tc.Start(); err != nil {
 		return 127
 	}
-	stopSignals := forwardSignals(cmd.Process)
+	stopSignals := forwardSignals(tc.Process)
 	defer stopSignals()
-	if err := cmd.Wait(); err != nil {
+	if err := tc.Wait(); err != nil {
+		if tc.timedOut() {
+			fmt.Fprintln(os.Stderr, tc.timeoutMessage())
+			return 124
+		}
 		if exitErr, ok := err.(*exec.ExitError); ok {
 			return exitErr.ExitCode()
 		}