refactor(library): replace BBCode editor with CKeditor for article text
- Switch article create/edit forms to CKeditor 5 (image upload disabled)
- Add ArticleTextRenderer: DOMDocument block-based pagination + HTMLPurifier/smilies render
- Convert .txt file uploads to HTML paragraphs on create
- Export TXT/FB2 via htmlToPlainText() instead of legacy BBCode notags
- Strip HTML tags in search excerpts and tag previews
- Fix Links::linkSeparator() bug (tags rendered as individual characters)
- Add install/library_text_converter.php to migrate BBCode → HTML in DB
- Add ArticleTextRenderer: DOMDocument block-based pagination + HTMLPurifier/smilies render
- Convert .txt file uploads to HTML paragraphs on create
- Export TXT/FB2 via htmlToPlainText() instead of legacy BBCode notags
- Strip HTML tags in search excerpts and tag previews
- Fix Links::linkSeparator() bug (tags rendered as individual characters)
- Add install/library_text_converter.php to migrate BBCode → HTML in DB