v0.2.2: Fix blank derived cells in monthly rows

Fix blank derived cells in monthly rows

v0.2.1: Fix monthly derived column calculation

Fixed an issue where derived formula columns could show correctly in the Total row but fail to calculate for individual monthly rows.

v0.2.0: Add formula-based derived columns

• Add derived columns with formula support
• Support references by column id, plus parentheses and abs(), min(), max()
• Handle missing values and division by zero safely
• Recalculate the Total row from the underlying totals for derived formulas
• Refresh the README with updated examples and configuration docs

Full Changelog: v0.1.1...v0.2.0

v0.1.1

Fix hidden-month row handling when hide_empty is enabled
Clean up export menu listener on detach
Ignore invalid configured year values

v0.1.0

Initial release.