fix(web): keep the action status fetch alive when a client disconnects

The status fetch used the request context. A client that dropped the
connection, such as a readiness probe with a one second timeout,
cancelled the fetch. The failure was then cached and every later
request showed no action status. The fetch now ignores the caller
cancellation and keeps its own timeout.

internal/web/actions_test.go

@@ -2,6 +2,7 @@ package web
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"io"
 	"log/slog"
@@ -407,3 +408,15 @@ func TestRedirectDoesNotForwardToken(t *testing.T) {
 		t.Fatal("bearer token forwarded across a redirect")
 	}
 }
+
+func TestStatusFetchSurvivesCancelledRequest(t *testing.T) {
+	fh := newFakeHook(t)
+	fh.statBody = `[{"repo":"o/r","url":"` + alertURL + `","state":"running"}]`
+	h := newActionServer(t, nil, fh.srv.URL)
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+	rows, err := h.actions.statusRows(ctx, h.actions.list[0])
+	if err != nil || len(rows) != 1 {
+		t.Fatalf("rows=%d err=%v, want the fetch to complete despite the cancelled request", len(rows), err)
+	}
+}