fix: gower normalization and site-based score_data return with no user data input

[jjmaynard]

Description

Code changes address issues #250 and #261

Issues Fixed

1. Incorrect Site Similarity: rank_soils returns site-based data scores even when users provide insufficient inputs. Gower's distance needs at least 2 variables - since elevation is auto-extracted, users must provide slope OR depth-to-bedrock for valid site-based data calculations.

2. Double Normalization: _gower_distance_row normalizes values already normalized by gower_distances, preventing proper soil reordering.

Changes

• Added validation to only calculate site scores when sufficient inputs provided
• Removed redundant normalization in _gower_distance_row

Test Cases

Incorrect Site Similarity: #250
Test point: {"lon": -72.68237, "lat": 41.66272}

Double Normalization: #261
Test point: : {"lon": -94.31005777, "lat": 42.63413723}
Location with Nicollet (clay loam) as top-ranked soil:

• Input: User enters 'loam' texture (similar to Clarion)
• Before: Nicollet incorrectly stays top-ranked
• After: Clarion correctly ranks highest
  Fixes accurate soil ranking based on user data.

[garobrik]

this code was merged to main in #266