docs: update README and memory notes

.memory/note.md

@@ -0,0 +1,3 @@
+- README is more detailed than memory files; keep memory compact.
+- Use `state.md` for evolving engine/demo/API details.
+- `project.md` should stay as a short pointer file.

.memory/project.md

@@ -0,0 +1,6 @@
+# Project memory
+
+- RPN calculator JS project.
+- Read `.memory/state.md` for current state.
+- Keep names and commands in English.
+- Update memory files based on events: engine, demo, API, commands, exports, docs, or tasks.

.memory/state.md

@@ -0,0 +1,7 @@
+# State
+- Core engine: `src/rpn-calculator.js`
+- Active demo: `samples/dev/` (HP48-style UI)
+- Public API: `push`, `pop`, `clear`, `swap`, `remove`, `edit`, `isValidIndex`, `input`, `command`, `getOperationsByCategory`, `getConstants`
+- Config: `maxSize`, `base`, `angleMode`, `enabledCommands`
+- Commands: arithmetic, stack, trigonometry, constants `pi` and `e`
+- Exports: browser `window.RpnCalculator`, CommonJS `module.exports`

.memory/todo.md

@@ -0,0 +1,4 @@
+- Keep `.memory/project.md` short.
+- Update `.memory/state.md` after project changes.
+- Reconcile README and demo docs if behavior changes.
+- Track future work around keyboard UX, stack selection, and command docs.

README.md

@@ -22,9 +22,10 @@ The main class is `RpnCalculator`.
 - `samples/calc-01/index.html`: active browser demo entry point
 - `samples/calc-01/index.css`: demo styles
 - `samples/calc-01/index.js`: demo UI and keyboard logic
-- `samples/calc-XX/index.html`: active browser demo entry point
-- `samples/calc-XX/index.css`: demo styles
-- `samples/calc-XX/index.js`: demo UI and keyboard logic
+- `samples/calc-01/index.html`: alternate browser demo entry point
+- `samples/calc-01/index.css`: alternate demo styles
+- `samples/calc-01/index.js`: alternate demo UI and keyboard logic
+- `samples/calc-XX/`: placeholder name for future demo variants
 
 ## Public API
 
@@ -129,6 +130,9 @@ calc.command('e');
 
 - `mod` is a percentage operator:
   - `a b % => (a * b) / 100`
+- `pow` accepts aliases `^` and `y^x`
+- `sqrt` accepts alias `sqrt(x)`
+- `recip` accepts alias `1/x`
 - `div` and `recip` throw `Division by zero` when needed
 - `sqrt` throws `Invalid input for sqrt` for negative values
 - `asin` and `acos` throw explicit domain errors outside `[-1, 1]`
@@ -138,6 +142,7 @@ calc.command('e');
 - `ln` uses `Math.log`
 - direct trigonometric functions convert input using `toRadians(...)`
 - inverse trigonometric functions convert results back using the current angle mode
+- `angleMode` supports `deg`, `rad`, and `grad`
 - formatted numeric values are rounded to 12 decimal places
 - `-0` is normalized to `0`
 - `inputValue` remains a string to preserve future non-decimal input support
@@ -261,6 +266,7 @@ The current demo supports:
 - `x`, `y`, `z`, `t`
 
 The demo also implements stack selection and stack-item move mode in its UI layer using the public calculator methods.
+It keeps the calculator screen focused and updates the visible stack window as the selection moves.
 
 ## Exports