test(workspace): accept only #249 decision markers and state the lint scope

The overlay lint accepted any D-number, so another issue's ruling such
as "D5 (#245)" could mark a concept override. A marker now has to be a
D-number with no other issue cited; the vocabulary rule that cited #245
reads "#245 decision 5". TESTING.md now states that the lint covers
workspace.css only, lists the unmarked overrides still in images.css,
and says PRs C and D run the lint over each page sheet they keep.

web/js/workspace/workspace.css

@@ -43,7 +43,7 @@ main:focus-visible { outline: 2px solid var(--ca-focus); outline-offset: 4px; }
 /* Long tag names wrap inside the Tag cell so the Actions column keeps its intrinsic width; on two-column screens the
    minimum keeps the concept's longest sample ("architecture", about 5em) on one line. */
 .vocabulary-main td:first-child { overflow-wrap: anywhere; min-width: calc(6em + 20px); }
-/* D5 (#245): bounded lists continue with Load more; never a scroll anchor, so appended rows push the end away. */
+/* Tags & categories (#245 decision 5): bounded lists continue with Load more; never a scroll anchor, so appended rows push the end away. */
 .vocabulary-main .vocabulary-continuation { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; padding-block: 15px 0; overflow-anchor: none; }
 .vocabulary-main .vocabulary-continuation p { margin: 0; flex: 1 1 200px; font-size: 12px; color: var(--ca-muted); }
 .vocabulary-main .vocabulary-continuation .vocabulary-error { color: var(--ca-error-text); }