feat(desktop): add offline cache and verified app updates

Clean release notes in Android and desktop update dialogs. Persist downloaded audio and offline playback events per server and user; add desktop update checks, checksum verification and installer launch.

packages/core/src/releases.ts

@@ -0,0 +1,16 @@
+/** Release bodies also contain CI build reports; these are not user-facing notes. */
+export function releaseNotesText(markdown: string): string {
+  return markdown
+    .replace(/<!--\s*([\w-]+-status)\s*-->[\s\S]*?<!--\s*\/\1\s*-->/gi, '')
+    .replace(/<!--[\s\S]*?-->/g, '')
+    .replace(/^\s*```[^\n]*\n[\s\S]*?^\s*```\s*$/gm, '')
+    .replace(/^\s{0,3}#{1,6}\s+/gm, '')
+    .replace(/^\s*>\s?/gm, '')
+    .replace(/!\[([^\]]*)\]\([^)]*\)/g, '$1')
+    .replace(/\[([^\]]+)\]\([^)]*\)/g, '$1')
+    .replace(/(`+)(.*?)\1/g, '$2')
+    .replace(/\*\*(.*?)\*\*|__(.*?)__/g, '$1$2')
+    .replace(/^\s*[-*+]\s+/gm, '• ')
+    .replace(/\n{3,}/g, '\n\n')
+    .trim();
+}