docs: add Records feature to README, update Observatory and Records screenshots

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: timothybrown

README.md

@@ -63,6 +63,17 @@ NOAA-style monthly and yearly climate summaries with daily breakdown tables show
 
 ![Climate Reports](screenshots/reports.png)
 
+### Station Records
+
+All-time, yearly, and monthly extremes across 6 categories: temperature, wind, rain, humidity, pressure, and solar. Each record shows the value and the date it was set. When an all-time record is broken today, a gold star badge appears on the corresponding Observatory card with a tooltip showing the previous record. Records are computed from continuous aggregates, so they stay fast even with years of data.
+
+<table align="center">
+  <tr>
+    <td align="center"><img src="screenshots/records-dark.png" alt="Station Records (dark)" width="100%" /></td>
+    <td align="center"><img src="screenshots/records-light.png" alt="Station Records (light)" width="100%" /></td>
+  </tr>
+</table>
+
 ### Diagnostics
 
 Battery levels, gateway stats, firmware info, and connection status. Useful for keeping an eye on sensor health.