ci: add four upstream bug-fix branches to manifest

All four are single-file Avatarsia-authored bug fixes that are
also open upstream PRs on openxe-org:

- fix/250-wiedervorlage-sidebar-counter (PR OpenXE-org#253)
  www/eproosystem.php +2/-2: reactivate Wiedervorlagen counter

- fix/dateien-stichwoerter-245 (PR OpenXE-org#246)
  classes/Modules/Api/Controller/Version1/FileController.php +2/-2:
  fix variable scoping in POST /v1/dateien stichwoerter

- fix/versandpakete-247 (PR OpenXE-org#248)
  classes/Modules/Api/Controller/Version1/TrackingNumberController.php +25:
  write tracking numbers into the versandpakete table so the UI
  shows them

- fix/player-custom-module-support (PR OpenXE-org#256)
  phpwf/class.player.php +12/-2: support _custom.php extension
  files for page controllers, analogous to class.erpapi_custom.php

Each branch is based on an older origin/master snapshot, but
since origin/master is strictly behind upstream/master (zero
divergent commits), git merges only the new commits during
integration without re-applying the upstream drift.

Author: Avatarsia

.github/integration-branches.txt

@@ -38,3 +38,9 @@ feature/row-highlight-clean
 fix/woocommerce-variation-support
 feature/paid-marking-clean
 mwst_korrektion
+
+# Upstream bug-fix PRs (single-file patches, also live as open PRs on openxe-org)
+fix/250-wiedervorlage-sidebar-counter
+fix/dateien-stichwoerter-245
+fix/versandpakete-247
+fix/player-custom-module-support