Add (optional) hideInNav option to plugin.json

[henryk86]

This PR adds support for a new optional hideInNav property in a plugin's plugin.json.
When set to true, the plugin remains available in TeddyCloud but is not added to the main navigation. This is useful for plugins that provide functionality or pages which should only be opened directly or from another plugin/page.

If hideInNav is omitted or set to false, the plugin behaves as before and is shown in the navigation.

I also introduced a filter for hidden plugins and pagination to the list.

Additionally, the language.json files were reordered consistently again. No existing translation content was changed as part of that cleanup.

Checks:

• old plugins without tis flag still working

[ditschi]

Thanks for the thorough work here. I tested this PR in the browser against a local build of the backend fix for #350, which makes /content/download/… honor tracks=: toniebox-reverse-engineering/teddycloud#553.

Result: no conflict, and some of the workarounds become unnecessary. I used a 4-track library TAF assigned to a tag via lib://…:

• PR as-is + backend fix: track download from the Tonie info dialog works (/content/…?special=library&ogg=true&tracks=2,3 → application/zip).
• PR with the URL rewrite and the lib:// resolution in TonieInformationModal removed + backend fix: the dialog uses the tag's audioUrl (/content/download/<ruid>/…&skip_header=true&ogg=true&tracks=2,3) and also gets a zip with exactly the two tracks. It works for any local TAF source, not just lib://.

Suggestion (your call, it's your PR):

• Once the backend fix is merged, drop the /content/download/ → /content/ rewrite in tafDownload.ts and the lib:// resolution in TonieInformationModal. That removes frontend per-source logic.
• Keep the lib:// resolution in FileBrowser.tsx for 500304E0.json. On the backend, /content/<dir>/500304E0.json?ogg=true returns 404 and …&tracks=… drops the connection, so that path still needs the resolved TAF URL.
• Keep the other two fixes, which are independent of the backend: the track selection reset on re-render, and the 500304E0.json download that came out as Ogg (useFileDownload.ts).

If you'd rather merge this PR as it is, that works too. Until the backend fix lands, your rewrite is what makes this work for lib:// sources.

One thing I haven't tested is non-lib:// local sources with the rewrite, since the rewrite was written for lib:// only.

[henryk86]

If it can be done in the backend, it should be done in the backend. I will remove the frontend Adaption of this url rewrite.