chat : Seed OSS thinking + tool call support (#15552)
* Reasoning and tool-calling support for Seed OSS
* Fix grammar and partial parsing
* Whitespace
* New chat template
* Update common/chat.cpp
Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>
* Update common/chat.cpp
Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>
* Remove unused 'purge_healing_marker' helper
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Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>
