This pull request refactors the transformation logic in the resources/plot.vl.json file to simplify and optimize how base counts (a, t, g, c) are extracted and calculated. The previous approach used multiple split, flatten, and aggregate operations for each base type, which has now been replaced with a more concise method that uses index searching and direct calculation. This should make the transformation pipeline easier to maintain and potentially improve performance.

Refactoring and simplification of transformation logic:

• Removed multiple split, flatten, and aggregate steps for extracting and aggregating base counts (a, t, g, c), reducing complexity in the transformation pipeline. [1] [2]
• Introduced a new approach that calculates a search_key for each position, finds the index of each base type in its respective string, and directly extracts the count using conditional logic and string slicing.