* fix(gallery): coalesce artifact download progress
Buffer high-frequency downloading events and forward only the latest event on a periodic tick. Flush progress synchronously at phase boundaries and shutdown to preserve ordering and final state.
Assisted-by: Codex:gpt-5
* fix(gallery): wire progress coalescing into model installs
Route artifact progress through the 250 ms coalescer and flush it on every model operation exit. Keep the legacy download callback unchanged.
Assisted-by: Codex:gpt-5
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Co-authored-by: Ettore Di Giacinto <mudler@localai.io>