feat: advanced filename templates, low-RAM device profiling, responsive artist UI, and project site

- Add advanced filename template placeholders: {track_raw}, {disc_raw}, {date},
  formatted numbers {track:N}/{disc:N}, and date formatting {date:%Y-%m-%d}
  with strftime-to-Go layout conversion and robust date parser
- Pass date/release_date metadata to filename builder in all providers
  (Amazon, Qobuz, Tidal, YouTube, extensions) and Flutter download queue
- Detect ARM32-only / low-RAM Android devices at startup and reduce image
  cache size and disable overscroll effects for smoother experience
- Make artist screen selection bar responsive: compact stacked layout on
  narrow screens or large text scale; add quality picker before track download
- Add advanced tags toggle in download settings filename format editor
- Fix ICU plural syntax in DE/ES/PT/RU translations (one {}=1{...} -> one {...})
- Add filenameShowAdvancedTags l10n strings (EN, ID) and regenerate dart files
- Fix featured-artist regex: remove '&' from split separators
- Add Go filename template tests (filename_test.go)
- Add GitHub Pages workflow and static project site

lib/constants/app_info.dart

@@ -1,8 +1,8 @@
 /// App version and info constants
 /// Update version here only - all other files will reference this
 class AppInfo {
-  static const String version = '3.6.6';
-  static const String buildNumber = '80';
+  static const String version = '3.6.7';
+  static const String buildNumber = '81';
   static const String fullVersion = '$version+$buildNumber';