Webui/prompt processing progress (#18300)

Webui/prompt processing progress (#18300)

* webui: display prompt preprocessing progress

* webui: add percentage/ETA and exclude cached tokens from progress

Address review feedback from ngxson

* webui: add minutes and first chunk (0%) case

* Update tools/server/webui/src/lib/components/app/chat/ChatMessages/ChatMessageAssistant.svelte

Co-authored-by: Aleksander Grygier <redacted>
* Update tools/server/webui/src/lib/components/app/chat/ChatMessages/ChatMessageAssistant.svelte

Co-authored-by: Aleksander Grygier <redacted>
* webui: address review feedback from allozaur

* chore: update webui build output

* webui: address review feedback from allozaur

* nit

* chore: update webui build output

* feat: Enhance chat processing state

* feat: Improve chat processing statistics UI

* chore: update webui build output

* feat: Add live generation statistics to processing state hook

* feat: Persist prompt processing stats in hook for better UX

* refactor: Enhance ChatMessageStatistics for live stream display

* feat: Implement enhanced live chat statistics into assistant message

* chore: update webui build output

* fix: Proper tab for each stage of prompt processing/generation

* chore: update webui build output

* fix: Improved ETA calculation & display logic

* chore: update webui build output

* feat: Simplify logic & remove ETA from prompt progress

* chore: update webui build output

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Co-authored-by: Aleksander Grygier <redacted>