refactor(photos): extract shared zero-padded PhotoRenumberer helper

Factor cache-on-save's renumberPhotos into a shared PhotoRenumberer class
(Grav\Plugin\Shared), the single owner of the photo-NN naming invariant used
by both the create/edit reconcile and the upcoming live reorder route, so their
numbering can't diverge.

Changes vs the old private method:
- Zero-pads to photo-01..NN (pad width grows with the set) so lexicographic
  media order equals numeric order past 9 photos — cover = images|first stays
  correct for 10+ photos. Normalises pre-existing un-padded photo-N on first pass.
- Image-extension guard moved into the helper: only real image files on disk are
  renamed, so a crafted manifest naming the entry .md, a .gpx or a .meta.yaml is
  skipped by every caller, not just cache-on-save.

Create-mode entries now also emit photo-01..NN — an intentional, accepted side
effect of sharing one helper.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

plugins/cache-on-save/cache-on-save.php

@@ -6,15 +6,17 @@ use Grav\Common\Plugin;
 use RocketTheme\Toolbox\Event\Event;
 
 require_once __DIR__ . '/classes/EntryScopeGuard.php';
+require_once __DIR__ . '/classes/PhotoRenumberer.php';
 
 use Grav\Plugin\Shared\EntryScopeGuard;
+use Grav\Plugin\Shared\PhotoRenumberer;
 
 class CacheOnSavePlugin extends Plugin
 {
     /**
      * onFormProcessed fires once per `process:` action (add_page, upload, message,
      * reset — 4x for the post form). Photo reconciliation must run exactly once:
-     * the first pass renames the kept photos to photo-1..N, so a second pass with
+     * the first pass renames the kept photos to photo-01..NN, so a second pass with
      * the same manifest would see those renamed files as "unlisted" and delete
      * them. This latches after the first run (the plugin instance persists for the
      * request); the first fire is the `add_page` action, after add-page-by-form
@@ -244,7 +246,7 @@ class CacheOnSavePlugin extends Plugin
             }
         }
 
-        $this->renumberPhotos($dir, $names);
+        PhotoRenumberer::renumber($dir, $names);
     }
 
     /**
@@ -276,38 +278,6 @@ class CacheOnSavePlugin extends Plugin
         }
     }
 
-    /**
-     * Rename the files named in $names to photo-1..N in that order, in $dir.
-     * Two-phase via temp names so a target (photo-2.jpg) can't clobber a
-     * not-yet-moved source of the same name.
-     */
-    private function renumberPhotos(string $dir, array $names): void
-    {
-        $planned = [];
-        $i = 1;
-        foreach ($names as $name) {
-            $src = $dir . DIRECTORY_SEPARATOR . $name;
-            if (!is_file($src)) {
-                continue; // skip anything not actually on disk
-            }
-            $ext = strtolower(pathinfo($name, PATHINFO_EXTENSION)) ?: 'jpg';
-            $tmp = $dir . DIRECTORY_SEPARATOR . '.reorder-tmp-' . $i . '.' . $ext;
-            $final = $dir . DIRECTORY_SEPARATOR . 'photo-' . $i . '.' . $ext;
-            if ($src === $final) {
-                $i++;
-                continue; // already correctly named
-            }
-            @rename($src, $tmp);
-            $planned[] = [$tmp, $final];
-            $i++;
-        }
-        foreach ($planned as [$tmp, $final]) {
-            if (is_file($tmp)) {
-                @rename($tmp, $final);
-            }
-        }
-    }
-
     /**
      * Locate the freshly-created entry folder: the child of the active trip's
      * dailies directory that contains all of the uploaded files. Matching by the