fix(growth): rank the rate board by a smoothed score

Show the real percentage on the card, but sort with delta / (baseline + prior) so a small baseline cannot dominate. Same-day publishes stay off the rate board.

tests/test_config.py

@@ -146,6 +146,7 @@ def test_analytics_defaults_and_validation():
         assert cfg.analytics.video_shrink_minutes == 60
         assert cfg.analytics.shrink_minutes is None
         assert cfg.analytics.home_growth_days == "auto"
+        assert cfg.analytics.growth_rate_prior == 500
         assert cfg.schedule.recent_snapshot_minutes == 60
         assert cfg.schedule.recent_video_days == 2
         assert cfg.schedule.snapshot_at == "23:15"
@@ -159,6 +160,7 @@ def test_analytics_defaults_and_validation():
             "video_shrink_minutes": 30,
             "shrink_minutes": 90,
             "home_growth_days": 1,
+            "growth_rate_prior": 1000,
         }
         data["schedule"] = {
             "discover_minutes": 30,
@@ -176,6 +178,7 @@ def test_analytics_defaults_and_validation():
         assert cfg.analytics.video_shrink_minutes == 30
         assert cfg.analytics.shrink_minutes == 90
         assert cfg.analytics.home_growth_days == 1
+        assert cfg.analytics.growth_rate_prior == 1000
         assert cfg.schedule.recent_snapshot_minutes == 15
         assert cfg.schedule.recent_video_days == 3
 
@@ -194,6 +197,7 @@ def test_analytics_defaults_and_validation():
             ({"home_growth_days": 3}, "home_growth_days"),
             ({"home_growth_days": "7"}, "home_growth_days"),
             ({"home_growth_days": 0}, "home_growth_days"),
+            ({"growth_rate_prior": -1}, "growth_rate_prior"),
         ):
             data = base_config()
             data["analytics"] = bad