Adds tier-based LLM routing so fast local models (vLLM, Ollama) handle
structured tasks while cloud models (Gemini, Anthropic) are reserved for
heavy reasoning. Single-provider configs continue to work via fallback.
- Tier type + ProviderRegistry with assignTier/getProvider/fallback chain
- Multi-provider config format: { providers: [{ name, type, tier, ... }] }
- NamedProvider wrapper for multiple instances of same provider type
- Setup wizard: Simple (legacy) / Advanced (fast+heavy tiers) modes
- Status display: tiered view with /llm/providers endpoint
- Call sites use getProvider('fast') instead of getActive()
- Full backward compatibility with existing single-provider configs
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
