add via_ip.estimate_location using binary search

my/location/fallback/via_home.py

@@ -22,10 +22,10 @@ class Config(user_config):
         ]]
     ]
 
-    # default ~1km accuracy
+    # default ~30km accuracy
     # this is called 'home_accuracy' since it lives on the base location.config object,
     # to differentiate it from accuracy for other providers
-    home_accuracy: float = 1000
+    home_accuracy: float = 30_000
 
     # TODO could make current Optional and somehow determine from system settings?
     @property