chore: bump version to 2026.3.1-beta1

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Olen

custom_components/plant/manifest.json

@@ -17,5 +17,5 @@
   "requirements": [
     "async-timeout>=4.0.2"
   ],
-  "version": "2026.2.1"
+  "version": "2026.3.1-beta1"
 }