refactor: MoA uses lightweight API references + SDK arbiter as aggregator

Instead of spawning separate processes or using OpenRouter, MoA now:
- Queries external API models (Kimi, GLM) in parallel for opinions
- Injects opinions into the SDK arbiter's prompt
- The existing subscription-based arbiter aggregates all perspectives

No extra SDK processes, no OpenRouter dependency. Per-model config via
MOA_REF_MODELS + MOA_{NAME}_MODEL/BASE_URL/API_KEY env vars.

.env.example

@@ -58,13 +58,17 @@ STATUS_CHANNEL_ID=                    # Discord channel ID for live status updat
 # ARBITER_FALLBACK_ENABLED=true         # Fall back to codex on Claude failure (default: true)
 
 # --- Mixture of Agents (MoA) ---
-# Queries multiple models in parallel for arbiter verdicts, then aggregates.
-# Requires OpenAI-compatible API (OpenRouter recommended for multi-model access).
+# Queries external API models in parallel before arbiter runs.
+# Their opinions are injected into the arbiter's prompt for better judgment.
+# The SDK arbiter (subscription-based, no extra cost) aggregates all perspectives.
 # MOA_ENABLED=true
-# MOA_BASE_URL=https://openrouter.ai/api/v1
-# MOA_API_KEY=sk-or-xxx
-# MOA_REFERENCE_MODELS=anthropic/claude-sonnet-4-6,openai/gpt-5.4,deepseek/deepseek-chat
-# MOA_AGGREGATOR_MODEL=anthropic/claude-opus-4-6
+# MOA_REF_MODELS=kimi,glm                         # Comma-separated reference model names
+# MOA_KIMI_MODEL=kimi-k2.5                        # Kimi model
+# MOA_KIMI_BASE_URL=https://api.kimi.com/coding   # Kimi API endpoint
+# MOA_KIMI_API_KEY=sk-kimi-xxx                    # Kimi API key
+# MOA_GLM_MODEL=glm-4-plus                        # GLM model
+# MOA_GLM_BASE_URL=https://open.bigmodel.cn/api/paas/v4  # GLM API endpoint
+# MOA_GLM_API_KEY=xxx                             # GLM API key
 
 # --- Advanced ---
 # MAX_CONCURRENT_AGENTS=5             # Max parallel agent processes