Split progress bar: blue for download, green for extraction

Left half (blue) shows download progress, right half (green) shows
extraction progress. When no extraction is active, full bar is blue.
Full bar = 50% blue (all downloaded) + 50% green (all extracted).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/renderer/styles.css

@@ -560,13 +560,19 @@ body,
   border-radius: 999px;
   background: var(--progress-track);
   overflow: hidden;
+  display: flex;
 }
 
-.progress > div {
+.progress-dl {
   height: 100%;
   background: linear-gradient(90deg, #3bc9ff, #22d3ee);
 }
 
+.progress-ex {
+  height: 100%;
+  background: linear-gradient(90deg, #22c55e, #4ade80);
+}
+
 table {
   width: 100%;
   table-layout: fixed;