webui: add setting for first-line chat titles (#21797)

webui: add setting for first-line chat titles (#21797)

* webui: add setting for first-line chat titles

Add an opt-in setting (`titleGenerationUseFirstLine`) to use the first
non-empty line of a prompt as the generated conversation title.

Previously, the complete multi-line prompt was being used, which created
long titles for complex queries. Coupled with
"Ask for confirmation before changing conversation title", the dialog
would overflow.

* Update tools/server/webui/src/lib/utils/text.ts

Co-authored-by: Aleksander Grygier <redacted>
* Update tools/server/webui/src/lib/utils/text.ts

Co-authored-by: Aleksander Grygier <redacted>
* webui: Run build to update the bundle

As requested in:
https://github.com/ggml-org/llama.cpp/pull/21797#pullrequestreview-4094935065

* webui: Fix missing import for NEWLINE_SEPARATOR

---------

Co-authored-by: Aleksander Grygier <redacted>