Add rule and script for plotting CBA indicators

[lisazeyen]

Add a rule and a script which plots the calculated B1 indicator.

[cdgaete]

Implementation Scope

Create visualizations for the B1 indicator (Total System Cost change) to support CBA analysis interpretation. The plots should:

1. Distribution overview - Show how projects are distributed between beneficial and non-beneficial, with clear separation at zero
2. Top projects ranking - Display projects ranked by benefit, breaking down the contribution of CAPEX vs OPEX changes
3. Cost composition analysis - Visualize the relationship between CAPEX and OPEX changes to understand what drives project benefits

Each plot should include project metadata (name, capacity, multi-border indicator) and be designed for extensibility to support future indicators (B2, B3, etc.).