Properly handle if missing title tag when write offline. The title eg. `Untitled post: Sunday, 17 December 2023, 18:53`

$_SERVER['REQUEST_URI'] is always url-encoded so we decoded it back before save it as a cache file.

Allows us to reuse previous uploaded images.
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See  #564

Add SECURITY.md also fix unexpected behavior with tags in number. See #614

Update de_DE.ini by @bttrx

Update it_IT.ini by @eagleman

Added the new strings

Add last modified time variable (eg. $p->lastMod). Add fallback just in case the tags count not the same.

Fixes i18n and unordered list; Provides i18n for feed error messages by @bttrx

Fixes i18n not fully shown for admin/popular view by @bttrx

Sort categories alphabetically in 'Categories' view by @bttrx

Fixes duplicate date.format IDs by @bttrx