fix: 修正行星事件边界与留点计算

- 统一 UT 事件时刻与 TT 查询时刻的边界判断
- 将外行星留点搜索锚定到对应冲日周期
- 修正水星、金星合日、留、大距事件选择
- 统一七大行星视位置计算辅助逻辑
- 增加公开 Last/Next 边界和 JPL/NAOJ 基线回归测试

basic/mercury_station_regression_test.go

@@ -0,0 +1,40 @@
+package basic
+
+import (
+	"math"
+	"testing"
+	"time"
+)
+
+func mercuryTTJDJST(year int, month time.Month, day, hour, minute, second int) float64 {
+	loc := time.FixedZone("JST", 9*3600)
+	return TD2UT(Date2JDE(time.Date(year, month, day, hour, minute, second, 0, loc).UTC()), true)
+}
+
+func TestMercuryTypedStationRegression1929(t *testing.T) {
+	loc := time.FixedZone("JST", 9*3600)
+	const tolerance = 30.0 / 86400.0
+
+	query := mercuryTTJDJST(1929, time.September, 20, 0, 0, 0)
+	wantP2R := mercuryTTJDJST(1929, time.September, 26, 1, 58, 0)
+	wantR2P := mercuryTTJDJST(1929, time.October, 16, 23, 32, 33)
+
+	nextP2R := NextMercuryProgradeToRetrograde(query)
+	nextR2P := NextMercuryRetrogradeToPrograde(query)
+	if math.Abs(nextP2R-wantP2R) > tolerance {
+		t.Fatalf("next P2R mismatch: got %s want %s", JDE2DateByZone(nextP2R, loc, false), JDE2DateByZone(wantP2R, loc, false))
+	}
+	if math.Abs(nextR2P-wantR2P) > tolerance {
+		t.Fatalf("next R2P mismatch: got %s want %s", JDE2DateByZone(nextR2P, loc, false), JDE2DateByZone(wantR2P, loc, false))
+	}
+
+	query = mercuryTTJDJST(1929, time.October, 20, 0, 0, 0)
+	lastP2R := LastMercuryProgradeToRetrograde(query)
+	lastR2P := LastMercuryRetrogradeToPrograde(query)
+	if math.Abs(lastP2R-wantP2R) > tolerance {
+		t.Fatalf("last P2R mismatch: got %s want %s", JDE2DateByZone(lastP2R, loc, false), JDE2DateByZone(wantP2R, loc, false))
+	}
+	if math.Abs(lastR2P-wantR2P) > tolerance {
+		t.Fatalf("last R2P mismatch: got %s want %s", JDE2DateByZone(lastR2P, loc, false), JDE2DateByZone(wantR2P, loc, false))
+	}
+}