docs: add comments to clarify elevation gain and loss handling in migrations regarding smallint

Author: JakobLichterfeld

lib/teslamate/log.ex

@@ -291,6 +291,8 @@ defmodule TeslaMate.Log do
             not is_nil(p.odometer),
         limit: 1
 
+    # If the sum of elevation gains exceeds the max value of a smallint (32767), set it to 0.
+    # If the sum of elevation losses exceeds the max value of a smallint (32767), set it to 0.
     elevation_data =
       from p1 in subquery(
              from p in Position,

priv/repo/migrations/20250613133700_add_and_calculate_elevation_changes.exs

@@ -7,6 +7,9 @@ defmodule TeslaMate.Repo.Migrations.AddAndCalculateElevationChanges do
       add :descent, :smallint
     end
 
+    # If the sum of elevation gains exceeds the max value of a smallint (32767), set it to 0.
+    # If the sum of elevation losses exceeds the max value of a smallint (32767), set it to 0.
+
     execute """
     WITH elevation_changes AS (
       SELECT