- fixed: search result always return empty
- add hashtag search: friendica_tag params
- ApiTest & api.md updated

image.preview: string (url for small image)

This should be tested on all supported PHP versions

Fix #6266

Part of #6263

Instead of red circle image, which breaks proxy module

Most important is to use `Photo::delete()` to have backend
to remove data.

- list registered backend
- set backend

This storage store files data in a separate database table

in store() if photo exists, don't update "created" timestamp

Edit mod/photos.php to use Photo model

https://dev.mysql.com/doc/refman/8.0/en/blob.html
BLOB and TEXT columns cannot have DEFAULT values.

This reverts commit 58bd75f8f3.

storage classes should implement this interface

- add backend related columns in photo table
- add system resource storage class
- add code to load image data from backend class
- return "nosign" image as photo meta with SystemResource backend

Set correct http response header, display error message using "404.tpl"