A Complex Calc

- Fixed the constants panel so it opens and closes reliably, including after rotation or an interrupted transition. - Improved complex-expression entry for adjacent terms, signed denominators, scientific notation, and incomplete exponents. - Made calculation history safer and more reliable across saves, migrations, corrupted data, and exact entry deletion. - Corrected published physical constants and localized constant names. - Fixed unit-conversion edge cases and made binary operations reject invalid input predictably. - Improved calculator, history, and constants layouts across rotation, safe areas, and interrupted transitions. - Fixed widget startup, bundled resources, paste, and update handling. - Smoothed button, gradient, and scrolling-label presentation while avoiding duplicate layers and gestures. - Improved the iPad launch presentation and credit-screen transitions.