Anthropic's Messages API rejects temperature > 1.0 with HTTP 400, but
_build_anthropic_payload forwarded it verbatim. The shipped "Nietzsche" preset
uses temperature 1.2 and the UI slider allows up to 2.0, so every Claude request
under such a preset hard-broke. Clamp into [0.0, 1.0] in the Anthropic builder
only (OpenAI keeps its wider 0.0-2.0 range). Covers all three Anthropic call
paths, which build through this one function. None is passed through unchanged.
Fixes#1615
Co-authored-by: Ethan <23321960+0xLeathery@users.noreply.github.com>