fix: prevent invalid bigint comparison with empty string in chart filters

[sentry]

This PR addresses a DataError (psycopg2.errors.InvalidTextRepresentation) that occurred when an empty string ('') was used as a filter value for a numeric column (e.g., bigint) in chart data previews. The root cause was that the apply_chart_filters function in charts_service.py was not type-aware and directly passed filter values to SQLAlchemy, resulting in invalid SQL like WHERE total_confirmed = ''.

To fix this, the following changes were implemented in ddpui/core/charts/charts_service.py:

• Introduced _NUMERIC_DATA_TYPES set and _is_numeric_data_type helper: To identify numeric column types.
• Added _coerce_filter_value function: This helper now intelligently handles filter values based on their declared data_type.
  • For numeric columns, an empty string ('') is coerced to None.
  • Non-empty strings are attempted to be cast to int or float.
  • If a non-empty string cannot be cast to a numeric type, the filter is skipped with a warning log.
• Implemented _build_eq_condition and _build_neq_condition: These functions generate IS NULL or IS NOT NULL clauses when the coerced value is None, ensuring correct SQL for null checks.
• Integrated type-aware processing into apply_chart_filters: The data_type field from the filter configuration is now read and used to apply the coercion logic before building SQLAlchemy WHERE clauses, preventing the generation of invalid SQL.

Fixes DALGO-BACKEND-28K

[siddhant3030]

this we can close.