fix: render actual newline in terminal-sanitized error messages

sanitize_for_terminal() escaped every control char it saw, including
plain LF, so any multi-line diagnostic built from a hardcoded template
(e.g. the path-separator error in main.rs) came out on a TTY as the
literal 4-character sequence "\x0A" instead of a line break.

LF cannot draw, move the cursor, or exfiltrate data the way ESC- and
CSI/OSC-initiated sequences can, so it does not need the same defense
as those. CR is still escaped since it can overwrite the current line
and forge fake output.

Closes #2104

CHANGELOG.md

@@ -4,7 +4,8 @@
 -
 
 ## Bugfixes
--
+- Render actual newlines instead of the literal `\x0A` escape in multi-line error
+  messages printed to a terminal, see #2104
 
 # 10.5.0