[DefKorns]

Next steps of restructuring om_vars in place, one menu at a time.

• Download path: themeGenerator, downloadTheme(s), installDownloaded, abortDownload, unpackTheme and getThemeList grouped in #### DOWNLOADS. A failed catalog download keeps the current theme list.
• Catalog cache: getThemeList fetches <sys>-list-v2.md5 first and skips the download when it matches the local copy. A release must publish the list and its .md5 together (build_catalog.sh <sys> --check in om_themes).
• Settings: grouped in #### SETTINGS. toggleFlag replaces settingsOptionChecker/toggleOptions, and settingsRows shows the clean-up and uninstaller rows. The separator now goes to settings/commands/.
• Toggles in place: the Settings toggles are INTERNAL and run the new om_toggle, so the Theme Manager reloads its list in place instead of relaunching, and the screen no longer flickers. om_theme and om_audio are gone.
• Upgrades: install deletes the renamed copy (cNNNN_x ↔ _x) of every shipped command row, which the previous version's uninstall leaves behind. _themeperfolder_1assign is now _themeperfolder_assign.

Tested on a SNES console: download path and cancel, catalog cache, the Settings functions in a sandbox (19 cases) and on the live screen. The install cleanup loop was tested on its own in busybox ash; a full install was not run.