docs(client): fix .suggestionChanged comment — bold weight, not underline (#331 review F1)

The header comment claimed the rule adds 'an underline'; it does not — it adds a
color-mix tint + font-weight:700, and the inner comment already notes text-
decoration is omitted on purpose. Aligned the header comment with the rule.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/client/src/features/comment/components/comment.module.css

@@ -55,7 +55,7 @@
 
 /* Intraline diff (#331): the fragment that actually changed within the
    red "before" / green "after" block. It inherits the surrounding red/green
-   framing and adds a stronger tint plus an underline so the eye lands on the
+   framing and adds a stronger tint plus bold weight so the eye lands on the
    changed letters/words (git/GitHub-style) rather than the whole line. The
    container's line-through (old) / green (new) still marks the full line. */
 .suggestionChanged {