fix(chrome): propagate caller ctx cancellation to CDP calls

InstallBundle, EvaluateExtractors, NextActionFromV8 ignored the caller
ctx and ran chromedp.Run on d.tabCtx alone, so step deadlines and
Ctrl-C couldn't interrupt an in-flight CDP round-trip on a hung tab.

Add a runCtx helper that derives a chromedp-bound context which also
cancels when the caller's ctx cancels, and route the three V8 entry
points through it.

internal/driver/chrome/driver_test.go

@@ -0,0 +1,44 @@
+package chrome
+
+import (
+	"context"
+	"testing"
+	"time"
+)
+
+// TestRunCtx_CallerCancelPropagates confirms that cancelling the caller's
+// context cancels the chromedp-bound context returned by runCtx. This is the
+// channel by which step deadlines and Ctrl-C reach in-flight CDP calls.
+func TestRunCtx_CallerCancelPropagates(t *testing.T) {
+	tabCtx, tabCancel := context.WithCancel(context.Background())
+	defer tabCancel()
+	d := &Driver{tabCtx: tabCtx}
+
+	callerCtx, callerCancel := context.WithCancel(context.Background())
+	derived, cancel := d.runCtx(callerCtx)
+	defer cancel()
+
+	callerCancel()
+	select {
+	case <-derived.Done():
+	case <-time.After(time.Second):
+		t.Fatal("derived ctx did not cancel after caller cancellation")
+	}
+}
+
+// TestRunCtx_TabCancelPropagates confirms the inverse: tearing down the tab
+// also cancels any in-flight derived context.
+func TestRunCtx_TabCancelPropagates(t *testing.T) {
+	tabCtx, tabCancel := context.WithCancel(context.Background())
+	d := &Driver{tabCtx: tabCtx}
+
+	derived, cancel := d.runCtx(context.Background())
+	defer cancel()
+
+	tabCancel()
+	select {
+	case <-derived.Done():
+	case <-time.After(time.Second):
+		t.Fatal("derived ctx did not cancel after tab cancellation")
+	}
+}