[desktop] Fix inline markdown input rules triggering mid-paragraph

[Codex]

Inline markdown shortcuts (*bold*, _italic_, etc.) only fired at line ends due to end-of-string regex anchors, breaking normal mid-paragraph typing.

• Input rules: Replaced $ end anchors with whitespace/end lookaheads so marks apply anywhere in a line while still requiring a boundary.
• Marks covered: Italic, bold, strikethrough (single/double tilde), and inline code now trigger after a space or line end.

Example:

// before: only matched at EOL
markRule(/\*([^*]+)\*$/, strong);

// after: matches before space or EOL
markRule(/\*([^*]+)\*(?=\s|$)/, strong);

Greptile Summary

Fixed inline markdown shortcuts to trigger mid-paragraph instead of only at line ends by replacing $ end-of-string regex anchors with (?=\s|$) lookaheads.

• All five inline mark rules (italic, bold, strikethrough variants, inline code) now trigger after typing a space or at line end
• Lookahead implementation correctly preserves whitespace while removing only the delimiter characters
• Improves natural typing flow - users can now format text mid-paragraph without workarounds

Confidence Score: 5/5

• This PR is safe to merge with no concerns
• The change is a well-isolated regex pattern fix that correctly uses positive lookaheads to preserve whitespace while triggering input rules mid-paragraph. The implementation properly handles the match boundaries and deletion logic.
• No files require special attention

Important Files Changed

Filename	Overview
apps/desktop/src/editor/Editor.tsx	Fixed inline markdown input rules to trigger mid-paragraph by replacing end-of-string anchors with lookaheads - implementation is correct and improves UX

_{Last reviewed commit: ac678f7}