test(helpers): setSystemSettingRestored — leave shared settings as found

The testuser-experience rule: the suite must leave shared settings
exactly as it found them. setSystemSettingRestored snapshots the prior
system_settings row, writes through the sanctioned API path (the only
one that reloads the settings registry — raw SQL leaves the cache
stale), and registers a cleanup restoring what WAS there, never a
hardcoded value.

setExtractorVersion now rides it, so the ev-pin tests no longer
restore scan_extractor_version to a hardcoded 1: a deliberate dev bump
of the extractor version survives a suite run instead of being
silently cancelled (the live dev server obeys that setting on its next
poll and would stop re-extracting parser fixes). The now-redundant
explicit t.Cleanup restores are removed from
TestExtractorVersionReextract and pinExtractorVersionOne.

cmd/server/tests/extractor_version_test.go

@@ -17,11 +17,9 @@ package main
 //	equal   → stable (second corruption persists)
 
 import (
-	"bytes"
 	"context"
 	"encoding/json"
 	"fmt"
-	"net/http"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -58,14 +56,11 @@ func corruptItemColumn(t *testing.T, setup *TestServerSetup, itemID pgtype.UUID,
 
 func setExtractorVersion(t *testing.T, setup *TestServerSetup, v int) {
 	t.Helper()
-	body, _ := json.Marshal(map[string]string{"key": "scan_extractor_version", "value": strconv.Itoa(v)})
-	req, _ := http.NewRequest("PUT", setup.Server.URL+"/api/system/settings", bytes.NewBuffer(body))
-	req.Header.Set("Content-Type", "application/json")
-	req.Header.Set("Authorization", "Bearer "+setup.Token)
-	resp, err := http.DefaultClient.Do(req)
-	require.NoError(t, err)
-	defer func() { _ = resp.Body.Close() }()
-	require.Equal(t, http.StatusOK, resp.StatusCode, "settings API is the only sanctioned write path")
+	// Restore-to-prior (not a hardcoded value): the shared dev DB's
+	// setting must survive the suite exactly as the test found it — if a
+	// parser-fix bump was in flight, a hardcoded 1 would silently cancel
+	// it and the live server would stop re-extracting.
+	setSystemSettingRestored(t, setup, "scan_extractor_version", strconv.Itoa(v))
 }
 
 func TestExtractorVersionReextract(t *testing.T) {
@@ -123,7 +118,8 @@ func TestExtractorVersionReextract(t *testing.T) {
 	// re-extract once: the corruption heals and the fresh manifest
 	// carries ev=2.
 	setExtractorVersion(t, setup, 2)
-	t.Cleanup(func() { setExtractorVersion(t, setup, 1) })
+	// Prior-value restore rides inside setExtractorVersion — never a
+	// hardcoded 1, so a deliberate dev bump survives the suite.
 	scanTestFolder(t, setup, admin, folder)
 	item, found = findAudioItemByPath(t, setup, libID, filepath.ToSlash("EV Probe Author/EV Probe Book/EV Probe Book.epub"))
 	require.True(t, found)
@@ -168,7 +164,8 @@ func TestExtractorVersionMultifile(t *testing.T) {
 	// Bump → the ev gate fires through multifileSidecarChanged → the
 	// editorial apply re-derives the title from the folder basename.
 	setExtractorVersion(t, setup, 2)
-	t.Cleanup(func() { setExtractorVersion(t, setup, 1) })
+	// Prior-value restore rides inside setExtractorVersion — never a
+	// hardcoded 1, so a deliberate dev bump survives the suite.
 	scanTestFolder(t, setup, admin, folder)
 	book, found = findAudioItemByPath(t, setup, libID, filepath.ToSlash("EV Audio Author/EV Audio Title"))
 	require.True(t, found)