* feat: implement structured outputs for Cerebras, OpenRouter, OpenAI, and Apple Intelligence
- Add structured output support with JSON schema in llm_client.rs
- Update actions.rs to use system prompt + user content approach
- Remove legacy ${output} variable substitution for supported providers
- Update Apple Intelligence Swift code to accept system prompts
- All providers now use consistent structured output format
- Remove duplicate check_apple_intelligence_availability function
* wip changes
* fix(structured-outputs): address PR #706 review comments
- Add settings migration to sync supports_structured_output field for existing providers
- Fix fallback behavior: structured output failures now fall through to legacy mode
- Clone api_key to prevent ownership issues in fallback path
- Clean up build_system_prompt(): remove placeholder entirely
(instead of replacing with 'the user's message' which reads awkwardly)
- Add warn import from log crate
* refactor(structured-outputs): apply best practice improvements
- Optimize settings migration: use single match instead of double iteration
- Add TRANSCRIPTION_FIELD constant to replace magic strings
- Keep Apple Intelligence behavior unchanged (no API fallback for privacy)
Addresses code review feedback on PR #706:
1. More efficient provider lookup in ensure_post_process_defaults()
2. Eliminates hardcoded 'transcription' string in JSON parsing
3. Maintains privacy-first approach for Apple Intelligence
* fix groq output
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Co-authored-by: CJ Pais <cj@cjpais.com>
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