[luisguzman-adfa]

What

The Update add-ons and Update build assets updaters now show one
monotonic progress bar with aggregate speed and total ETA, a "Checking for
updates..." state, and a result that says whether the content was already up to
date or a new version was installed. The fix lives in the shared path, so the
add-ons/assets duplication is removed and a new download module inherits the
behavior.

How

• Box: downloadWithAria2 aggregates progress across all files through
  aria2's RPC (piece-accurate completedLength): overall percent, aggregate
  speed, and total ETA on the job. Add-ons supplies the total from its staged
  catalog; assets uses aria2's learned totals. aria2 is shut down on queue drain
  (it does not exit on its own under RPC); the console readout stays as the
  fallback. New eta field through jobs.ts / routes.ts. No mirror change.
• App: new ContentUpdater interface + shared ContentUpdaterView (progress
  block, checking state, percent/speed/ETA line, terminal
  done/up-to-date/failed/cancelled, and the listener-lifecycle guard that fixes
  the initial-paint race). AddonsUpdater / CodeAssetsUpdater are thin
  adapters; the duplicated AddonsRefresh / CodeAssetsRefresh are deleted;
  ModuleActions is rewired.
• Control unchanged: pause / resume / cancel / retry go through the box job
  engine's process kill, not RPC (RPC is read-only progress); the metered-network
  consent stays app-side before the download. The withRetry reconnect indicator
  is re-surfaced from the poller.

UI

The add-ons and build-assets module updaters (the inline progress under the
Update button). Light and dark + device verification pending.

Strings

New UI strings, localized to all 33 locales before merge:

Key	Value
k2go_update_checking	Checking for updates...
k2go_eta_min_sec	%1$d min %2$d s left
k2go_eta_sec	%1$d s left
k2go_code_addons_update_up_to_date	Add-ons already up to date
k2go_code_assets_update_up_to_date	Build assets already up to date

Verification

• Dashboard tsc green; app compileStandardDebugJavaWithJavac green.
• Two-pass code review done (2 correctness bugs fixed).
• Device test pending.