perf fix + ad guard for the games grid, search section cleanup

- drop backdrop-filter from .game tiles (likely cause of a freeze-on-load
  bug on heavy uncached loads) and harden tile sizing so it can't balloon
  regardless; fix some long-dead CSS selectors along the way (mobile
  breakpoints were silently never applying)
- strip AdSense in-feed ads if they try to inject into the games grid
- top games / starred / recently played now only show a section if
  something inside it still matches the current search or tag filter,
  instead of leaving orphaned tiles with no header or stale clutter
- remove the proxy nav card from home (dead now that it's disabled)
- delete cookie.js and savedownload.js, confirmed fully unreferenced
  dead code superseded by the save/load flow already in settings.html

css/games.css

@@ -1,6 +1,9 @@
 .game {
     width: 20vw;
     height: 9vh;
+    min-height: 64px;
+    max-height: 9vh;
+    overflow: hidden;
     background-color: color-mix(in srgb, var(--color-2) 40%, #00000000 60%);
     display: flex;
     justify-content: center;
@@ -9,17 +12,17 @@
     border-radius: 20px;
     margin: 15px;
     /* transition-duration: 0.25s; */
-	backdrop-filter: blur(2px);
     box-shadow: 0 0 10px var(--color-2);
     text-decoration: none;
     content-visibility: auto;
-    contain-intrinsic-size: auto 9vh;
+    contain-intrinsic-size: 20vw 9vh;
 }
 .game:hover {
     transform: scale(1.1);
 }
 .game img {
     height: calc(100% - 4px - 4px);
+    max-height: calc(9vh - 8px);
 	border-radius: 15px;
 	aspect-ratio: 1 / 1;
     margin: 4px;
@@ -182,11 +185,6 @@ body {
 #gamesort:hover {
     filter: brightness(1.1);
 }
-@-moz-document url-prefix() {
-  game {
-    backdrop-filter: blur(0);
-  }
-}
 warnings {
     position: absolute;
     top: 0px;
@@ -218,17 +216,16 @@ warning {
     background-color: rgb(118, 118, 118);
     box-shadow: 0 0 10px rgb(193, 193, 193);
 }
-body[fast] game {
+body[fast] .game {
     background-color: color-mix(in srgb, var(--color-2) 70%, #000000 30%);
-	backdrop-filter: blur(0);
 }
 @media screen and (max-width: 900px) {
-	game {
+	.game {
 	  width: 40vw;
 	}
 }
 @media screen and (max-width: 660px) {
-	game {
+	.game {
 	  width: 60vw;
 	}
 }