* feat: added a generic openai endpoint provider for self-hosted models
* feat: proper vision and tool checkbox for generic endpoint
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Co-authored-by: hugo <hugoms@me.com>
- Add SecureKeyStore class using safeStorage encrypt/decrypt with base64 in SQLite
- Update chatHandlers to store/retrieve API keys via SecureKeyStore
- Delete old plain-text opencode_api_key on startup (no migration, re-enter key)
- Add deleteSetting() to ChatEngine
- Add 14 SecureKeyStore unit tests and 6 chatHandlers keychain integration tests
- Update existing chatHandlers test mocks for SecureKeyStore
- Update MISTRAL_PLAN.md: mark PR 1 done, remove legacy fallback from PR 2 scope