fix: Validate chart sort columns to prevent BigQuery ORDER BY errors

[sentry]

This PR addresses DALGO-BACKEND-29G, a DatabaseError occurring when BigQuery receives an ORDER BY clause referencing a column that is neither part of the GROUP BY dimensions nor an aggregated metric.

The root cause was identified in ddpui/core/charts/charts_service.py::apply_chart_sorting(). Previously, if a sort column was not a recognized metric alias, it was blindly treated as a dimension and passed directly to the ORDER BY clause. This led to BigQuery rejecting the query if the column was not actually a grouped dimension.

The fix introduces validation within apply_chart_sorting(). Before adding a sort column to the query builder, it now checks if the column is either a metric alias or one of the chart's grouped dimensions (obtained via normalize_dimensions(payload)). If the column does not meet these criteria, it is skipped, and a warning is logged, preventing the generation of an invalid BigQuery query.

Fixes DALGO-BACKEND-29G

[sentry]

Codecov Report

❌ Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.64%. Comparing base (75cb6fd) to head (b4881ac).

Files with missing lines	Patch %	Lines
ddpui/core/charts/charts_service.py	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1387      +/-   ##
==========================================
- Coverage   58.66%   58.64%   -0.03%     
==========================================
  Files         132      132              
  Lines       15690    15696       +6     
==========================================
  Hits         9205     9205              
- Misses       6485     6491       +6     

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