Better BNS2 calibration

.github/copilot-instructions.md

@@ -27,6 +27,7 @@ applyTo: '/**'
 
 * The documentation for quantflow is available at `https://quantflow.quantmid.com`
 * Documentation is built using [mkdocs](https://www.mkdocs.org/) and stored in the `docs/` directory. The documentation source files are written in markdown format.
+* Split prose into short paragraphs (one idea per paragraph) separated by blank lines. Never write a wall-of-text paragraph that strings together mechanism, rationale, caveats and usage advice. This applies to mkdocs tutorials, theory pages and long docstrings.
 * Do not use dashes (em dashes, en dashes, or hyphens used as dashes) in documentation files or docstrings. Use colons, parentheses, or restructure the sentence instead.
 * Math in documentation and docstrings: always use `\begin{equation}...\end{equation}` for any formula or equation. Use `$...$` only for brief inline references to variables (e.g. $F$, $K$). Do not use `$$...$$`, `` `...` ``, or RST syntax (`.. math::`, `:math:`).
 * Math notation convention: use $\Phi$ for the characteristic function and $\phi$ for the characteristic exponent, where $\Phi = e^{-\phi}$.