feat: add root command and fix calc-02 exponent shortcuts

README.md

@@ -7,7 +7,7 @@ A browser-friendly RPN calculator built around a small, generic JavaScript API.
 This project provides:
 
 - a reusable JavaScript RPN engine in `src/rpn-calculator.js`
-- a browser demo in `samples/dev/`
+- browser demos in `samples/dev/` and `samples/calc-02/`
 - a command system centralized in a single operation dictionary
 - a small public API focused on stack operations and generic command dispatch
 
@@ -24,7 +24,7 @@ The main class is `RpnCalculator`.
 - `samples/calc-01/index.js`: demo UI and keyboard logic
 - `samples/calc-02/index.html`: new responsive HP48GX-style demo entry point
 - `samples/calc-02/index.css`: new responsive demo styles
-- `samples/calc-02/index.js`: new demo UI and keyboard logic
+- `samples/calc-02/index.js`: responsive HP48GX-style demo UI and keyboard logic
 - `samples/calc-XX/`: placeholder name for future demo variants
 
 ## Public API
@@ -110,6 +110,7 @@ calc.command('e');
 - `div` alias: `/`
 - `mod` alias: `%`
 - `pow` aliases: `^`, `y^x`
+- `root` aliases: `y√x`, `yroot`, `nroot`
 - `sqr`
 - `neg`
 - `sqrt` alias: `sqrt(x)`
@@ -134,6 +135,7 @@ calc.command('e');
 - `sqrt` accepts alias `sqrt(x)`
 - `recip` accepts alias `1/x`
 - `div` and `recip` throw `Division by zero` when needed
+- `root` computes the y-th root as `x^(1/y)` and throws `Invalid input for root` for invalid inputs
 - `sqrt` throws `Invalid input for sqrt` for negative values
 - `asin` and `acos` throw explicit domain errors outside `[-1, 1]`
 - `log` throws `Invalid input for log` for values `<= 0`
@@ -270,8 +272,8 @@ It keeps the calculator screen focused and updates the visible stack window as t
 
 ## Calc 02 demo
 
-`samples/calc-02/` is a new responsive HP48GX-inspired demo.
-It adapts its layout to the browser window and switches between the supplied portrait and landscape arrangements.
+`samples/calc-02/` is a responsive HP48GX-inspired demo.
+It adapts its layout to the browser window, supports portrait and landscape arrangements, and includes the `y√x` root operation.
 
 ## Exports