* feat(studio): save load settings in chat presets
Presets previously stored only sampling params (temperature, top_p, etc.).
Extend them with an optional loadConfig blob that captures context length,
KV cache dtype, speculative decoding, and GPU layer knobs from the current
runtime when saving.
- Apply loadConfig when switching presets or hydrating on startup
- Show a short summary under the preset controls
- Prompt to reload when a model is already loaded
Fixes#7347
* fix(studio): persist preset loadConfig and capture GGUF context
Add ChatPresetLoadConfig to the chat settings API schema so presets with
load settings no longer 400 on save. Capture effective GGUF context from
ggufContextLength when customContextLength is cleared after auto-mode load.
* fix(studio): address Codex review on preset load settings
Coalesce default maxSeqLength/speculative/gpu knobs when capturing presets,
no-op apply for legacy presets without loadConfig, preserve GPU pin on apply,
and stop replaying stale loadConfig during settings hydration.
* Remove unused getOrderedPresets import
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Co-authored-by: Daniel Han <danielhanchen@gmail.com>
