iOS 1.0 RC 1: battery and heat work, version label, web player redraw tweaks

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ios/Stemify/Stems/StemServer.swift

@@ -70,9 +70,11 @@ final class StemServer: @unchecked Sendable {
             index = StemIndex(parsed.tracks, roots: roots())
         }
         // stemd on the server separates new music around the clock; look for its new stems
-        // every minute. Unchanged indexes cost one 304.
+        // every minute. Unchanged indexes cost one 304. Neither loop runs while nobody's looking:
+        // a radio wake every few seconds is most of a locked phone's battery drain.
         Task.detached { [weak self] in
             while let self {
+                await AppActivity.untilActive()
                 await self.refresh()
                 try? await Task.sleep(nanoseconds: Self.checkSeconds * 1_000_000_000)
             }
@@ -80,6 +82,7 @@ final class StemServer: @unchecked Sendable {
         // Watch stemd's queue: every few seconds while it has work, slowly when idle.
         Task.detached { [weak self] in
             while let self {
+                await AppActivity.untilActive()
                 await self.pollQueue()
                 try? await Task.sleep(nanoseconds: (self.busy ? 4 : 30) * 1_000_000_000)
             }