Post URLs and author URLs were interpolated raw into <a href> attributes
(and the raw user URL from empty_fetched into caption text), so crafted
links could break the HTML parse and fail the send with a 400. All
attribute interpolations now use encode_double_quoted_attribute; text
stays encode_text.
Both matched URL substrings anywhere in text, so a link like
https://evil.com/?u=pixiv.net/artworks/1 triggered a real fetch and
cache-key pollution. Prefix ^(?:https?://)? like the twitter pattern.
Apply rustfmt to the 11 files that had drifted (86 hunks): x-media
site modules (bsky/pixiv/twitter) and xmedia-bot (config/main/
photo/send). Formatting only - no semantic changes; full test suite
still green.