Issue
Title: CDSL CAS: Mutual Fund holdings show incorrect (zero) current value for certain row formats
Description
When parsing CDSL Consolidated Account Statements (CAS), some Mutual Fund holdings rows are incorrectly processed, leading to a reported current value of zero. This happens for a specific row variant where a distribution mode column (e.g., ARN/DIRECT) is present, but there is no separate "invested / total cost" column. In these cases, the row contains only three numeric columns: units, NAV, and current value.
Actual Behavior: The current value for such holdings is parsed as 0, which also results in an incorrect (lower) total balance for the MF-Folios. Expected Behavior: The current value should be correctly extracted from the third numeric column in these specific rows, and the total MF-Folios balance should accurately reflect the sum of all holdings' current values.
Task
Modify the repository so that the issue described above is resolved. The task's test suite verifies your patch by applying it on top of the base commit 226c7d016abe and running the modified tests.