fix(installer): re-enable version-incompatible apps after appstore update

[miaulalala]

Summary

• When a Nextcloud server is upgraded to a new major version, apps incompatible with the old version range are automatically disabled. Updating such an app via the web UI or occ app:update would upgrade the files but leave the app disabled, requiring a manual re-enable or reinstall.
• updateAppstoreApp() now checks whether the app was disabled due to version incompatibility before downloading the update. After a successful upgradeApp(), if those conditions were true, enableApp() is called automatically.
• Adds debug logging to previously-silent return false paths in isUpdateAvailable() (git-installed app, no newer version, app not in store) — this was causing update failures to appear as "keine Hinweise" (no hints) in debug logs.

Context

Reported in nextcloud/files_mindmap#269 — users upgrading from NC 31 to NC 32+ had files_mindmap auto-disabled during the server upgrade (old version declared max-version="31"). Clicking "Update" in the web UI downloaded the new compatible release but did not re-enable the app, so it remained invisible/broken until manually re-enabled.

cc @AndyScherzinger

Test plan

• New unit tests in tests/lib/InstallerTest.php cover the four cases: re-enable on incompatible-disabled, no re-enable on compatible-disabled (manually disabled), no re-enable on already-enabled, no re-enable when upgrade itself fails
• Manual test: install an app with max-version below current NC, trigger server upgrade to auto-disable it, then update via web UI and confirm the app is re-enabled
• Check debug log output now shows specific reason when isUpdateAvailable() returns false

🤖 Generated with Claude Code

[AndyScherzinger]

successfully tested. With this branch I am able to active i.e. the files_mindmap app from v33 max to a new version up to v35 version range on a v35 server with having dropped in the v33 max version first.

---

{"reqId":"IEqIbEHPliZh4De0HshB","level":0,"time":"2026-08-10T11:16:10+00:00","remoteAddr":"192.168.21.3","user":"admin","app":"updater","method":"POST","url":"/ocs/v2.php/apps/appstore/api/v1/apps/update","scriptName":"/ocs/v2.php","message":"App files_mindmap is disabled; incompatible with NC 35.0.0.1: yes","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:153.0) Gecko/20100101 Firefox/153.0","version":"35.0.0.1","data":{"app":"updater"}}

---

{"reqId":"IEqIbEHPliZh4De0HshB","level":1,"time":"2026-08-10T11:16:12+00:00","remoteAddr":"192.168.21.3","user":"admin","app":"updater","method":"POST","url":"/ocs/v2.php/apps/appstore/api/v1/apps/update","scriptName":"/ocs/v2.php","message":"Re-enabling files_mindmap after update: it was disabled due to version incompatibility","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:153.0) Gecko/20100101 Firefox/153.0","version":"35.0.0.1","data":{"app":"updater"}}

[miaulalala]

/backport to stable34

[miaulalala]

/backport to stable33

[miaulalala]

/backport to stable32