[kasnder]

Users looking for a custom blocklist in Advanced options currently find “Additional host files”, with no explanation that Minimal mode ignores them. Adding a URL also saves it without downloading its contents (#956).

Rename the setting to “Custom blocklists”, explain the HTTPS hosts-file format, and keep list management available in every mode of the GitHub/F-Droid builds. Show a persistent notice for Minimal and Research modes. The Play build hides blocklist management, manual updates and automatic-update controls, and rejects direct entry to the blocklist screen. Those ineffective controls were exposed before this PR. In active modes, explain that browser tracker protection defaults off.

Adding or editing a list now queues the existing download worker immediately. Offline requests wait for connectivity, cached hosts remain intact until downloading succeeds, and the screen shows pending work, per-list timestamps and errors. An Update action allows retries; list mutations are disabled during running downloads but remain available while waiting offline. Enabling an uncached list also queues a download. Filtering policy is unchanged.

Validation:

• 11 focused GitHub JVM tests and 2 Play JVM tests pass (the download test is intentionally skipped on Play), covering queued downloads, activity recreation, flavour-specific visibility in both settings levels and direct activity entry, screen actions, and existing HTTP download behaviour.
• GitHub Android lint passes; GitHub instrumentation tests compile.
• Inspected 320dp renders for Minimal, empty-list and downloading states.
• git diff --check passes.
• No physical-device or live-network test performed.

Addresses #956; the reporter's exact blocklist and configuration remain unknown.