feat(app): allow external apps to hide statusbar via manifest flags

- Add parseAppFlagsString() in AppManifestParsing.cpp to parse comma-separated flags (HideStatusBar, Hidden, None)
- Parse [app]flags in V1 and app.flags in V2 manifests
- Loader already supports HideStatusBar, GuiService hides statusbarWidget when set
- Enables fullscreen for ELF apps (e.g. BibleVerse, BookPlayer) without firmware recompilation of internal manifests
- Add tests for flag parsing (38 tests passing)
- Tested on es3c28p /dev/cu.usbmodem1101 @ 192.168.68.133 with HelloWorld app

Tactility/Source/app/AppManifestParsingV2.cpp

@@ -71,6 +71,12 @@ bool parseManifestV2(const std::map<std::string, std::string>& map, AppManifest&
         return false;
     }
 
+    // Optional: app.flags - e.g. "HideStatusBar" or "HideStatusBar,Hidden"
+    auto flags_it = map.find("app.flags");
+    if (flags_it != map.end()) {
+        manifest.appFlags = parseAppFlagsString(flags_it->second);
+    }
+
     return true;
 }