feedback5 R5: split the match screen's standalone pieces out

The match-ended plate, the solo pause plate, the highlight styles and
keepEarly now live in public/js/screens/game/*.js. game.js stays the screen
entry. MatchScreen stays one component. Imports only those pieces used moved
with them. Two source pins follow the lines that moved.

test/ui/playtest6-elite.test.js

@@ -171,6 +171,6 @@ describe('shop bar: the merge tag and the armed card', () => {
     assert.match(src, /onArm=\$\{setArmedCard\}/, 'ShopBar reports the armed card');
     assert.match(src, /mergeTarget\(priv, armedCard\.id, gd\.chess\)/, 'the target comes from gameLogic.mergeTarget');
     assert.match(src, /view\.highlightTiles\(mergeAt \? \[\[mergeAt\.row, mergeAt\.col\]\] : \[\], MERGE_HL\)/, 'its own highlight group (cleared with [])');
-    assert.match(src, /const MERGE_HL = Object\.freeze\(\{ group: 'mergeTile'/);
+    assert.match(read('public/js/screens/game/marks.js'), /const MERGE_HL = Object\.freeze\(\{ group: 'mergeTile'/);
   });
 });