agent_panel: alerts use the macro persona's verdict; all 4 takes still logged

agent_panel.verdict_source defaults to "macro": the macro take's stance is the
verdict, the synthesizer call is skipped (4 LLM calls per panel instead of 5);
"chair" restores the four-voice consensus + OPPOSE guard. Verdict source is
cached per mode and logged (panel_verdict_source). 406 tests.

Claude-Session: https://claude.ai/code/session_01FC4s6VCURFte4dub4xKxYL

config.json.example

@@ -46,7 +46,8 @@
     "reuse_ttl_seconds": 3600,
     "candles_enabled": true,
     "candle_bars_primary": 20,
-    "candle_bars_confirm": 10
+    "candle_bars_confirm": 10,
+    "verdict_source": "macro"
   },
   "market_outlook": {
     "enabled": false,