- Remove `is_proxy_target` field from Provider struct (Rust & TypeScript)
- Remove related DAO methods: get_proxy_target_provider, set_proxy_target
- Remove deprecated Tauri commands: get_proxy_targets, set_proxy_target
- Add `is_available()` method to CircuitBreaker for availability checks
without consuming HalfOpen probe permits (used in select_providers)
- Keep `allow_request()` for actual request gating with permit tracking
- Update stream_check to use failover_queue instead of is_proxy_target
- Clean up commented-out reset circuit breaker button in ProviderActions
- Remove unused useProxyTargets and useSetProxyTarget hooks
Remove the skillsPath field from SkillRepo and Skill structs since
recursive scanning now automatically discovers skills in all directories.
Simplify the UI by removing the path input field.
Add recursive directory scanning to discover SKILL.md files in nested
directories. When a SKILL.md is found, treat sibling directories as
functional folders rather than separate skills.