feat: push_gate 判定分支加结构化日志

force/推送/静默日/无更新仍推 四分支各记一条 logger.info,
无人值守时可定位「早报没推是静默日还是别的原因」(T7)。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

daily/push_gate.py

@@ -2,11 +2,14 @@
 
 from __future__ import annotations
 
+import logging
 from dataclasses import dataclass, field
 from typing import Any
 
 from daily.config import force_push, skip_push_when_silent
 
+logger = logging.getLogger(__name__)
+
 
 @dataclass
 class PushGateResult:
@@ -34,6 +37,7 @@ def evaluate_push_gate(
     featured_pick: dict[str, Any] | None,
 ) -> PushGateResult:
     if force_push():
+        logger.info("push_gate: force_push=on, 强制推送")
         return PushGateResult(should_push=True, reasons=["force_push"], silent=False)
 
     reasons: list[str] = []
@@ -48,4 +52,10 @@ def evaluate_push_gate(
 
     should = bool(reasons)
     silent = not should and skip_push_when_silent()
+    if should:
+        logger.info("push_gate: 推送 (原因: %s)", ",".join(reasons))
+    elif silent:
+        logger.info("push_gate: 静默日, 跳过推送 (无任何更新信号)")
+    else:
+        logger.info("push_gate: 无更新但 skip_push_when_silent=off, 仍推送")
     return PushGateResult(should_push=should, reasons=reasons, silent=silent)