controller v0.267.0: tests off DooPlex's Docker, cut-off copies refused, two pages true

R-650: internal/dockerexec — every docker exec routed through it; under
go test a real docker is refused (opt-in FELHOM_TEST_REAL_DOCKER=1; a stub
under the temp dir is allowed). api/stacks/web tests run under a silent
stub (TestMain). TestR650_NoBareDockerExec pins it repo-wide.
R-640: a dump without its engine's completion marker is refused before
the first mutation (unit + off-site restore) and again before any load.
R-499: the Tier-2 page's system-disk sentence has four true branches.
R-518: the backup button states the measured ~8 min stop.
R-626: measured on 9202, not reproduced.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/selfupdate/updater.go

@@ -5,12 +5,12 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"gitea.dooplex.hu/admin/felhom-controller/internal/dockerexec"
 	"gitea.dooplex.hu/admin/felhom-controller/internal/util"
 	"io"
 	"log"
 	"net/http"
 	neturl "net/url"
-	"os/exec"
 	"strings"
 	"sync"
 	"time"
@@ -858,7 +858,7 @@ func (u *Updater) VerifyStartup() *UpdateState {
 // runCommand executes a command and returns combined stdout+stderr and error.
 // Package var so tests can fake the docker CLI (no real exec in unit tests).
 var runCommand = func(name string, args ...string) (string, error) {
-	cmd := exec.Command(name, args...)
+	cmd := dockerexec.Command(name, args...)
 	var out bytes.Buffer
 	cmd.Stdout = &out
 	cmd.Stderr = &out
@@ -870,7 +870,7 @@ var runCommand = func(name string, args ...string) (string, error) {
 // `docker login --password-stdin` so the token is never in argv/ps). Returns combined output.
 // Package var so tests can fake the docker CLI.
 var runCommandStdin = func(stdin, name string, args ...string) (string, error) {
-	cmd := exec.Command(name, args...)
+	cmd := dockerexec.Command(name, args...)
 	cmd.Stdin = strings.NewReader(stdin)
 	var out bytes.Buffer
 	cmd.Stdout = &out