fix(keymap): match remaining letter shortcuts by typed character (#292)

#291 named letter keys by the typed character (e.key) when Alt is not held, so AZERTY Ctrl+Z is no longer Ctrl+W. Hard-coded handlers still compared the physical KeyboardEvent.code. A shared letterOf(e) in platform/keymap.ts now backs strokeOf and those handlers:

- terminal Ctrl+Shift+C / V / T (copy, paste, new tab) and Ctrl+letter control codes
- Run/Debug Configurations Ctrl/Cmd+N
- browser shortcut guards (blocked reload/print etc.)

Alt combos keep the physical key (Option / AltGr type symbols).

src/platform/keymap.ts

@@ -253,15 +253,25 @@ const CODE_NAMES: Record<string, string> = {
   NumpadDivide: "NumpadDivide",
 };
 
+/**
+ * The uppercase ASCII letter of a key event: the character it types when Alt
+ * is not held (on AZERTY the Z key sits on the physical KeyW, so Ctrl+Z must
+ * not read as Ctrl+W), or the physical `KeyX` when Alt is held (⌥ on macOS and
+ * AltGr may type a symbol) or `e.key` is not an ASCII letter.
+ */
+export function letterOf(e: Pick<KeyboardEvent, "code" | "key"> & { altKey?: boolean }): string | null {
+  if (/^[a-zA-Z]$/.test(e.key) && !e.altKey) return e.key.toUpperCase();
+  if (/^Key[A-Z]$/.test(e.code)) return e.code.slice(3);
+  return null;
+}
+
 /** Converts a keydown event into a canonical stroke, or null for bare modifiers. */
 export function strokeOf(
   e: Pick<KeyboardEvent, "code" | "key" | "metaKey" | "ctrlKey" | "altKey" | "shiftKey">,
 ): string | null {
   let key: string | undefined;
-  // A letter is named by the character it types: on AZERTY the Z key sits on the physical KeyW,
-  // so Ctrl+Z must not read as Ctrl+W. Alt combos may type a symbol (⌥ on macOS, AltGr), so they keep the physical key.
-  if (/^[a-zA-Z]$/.test(e.key) && !e.altKey) key = e.key.toUpperCase();
-  else if (/^Key[A-Z]$/.test(e.code)) key = e.code.slice(3);
+  const letter = letterOf(e);
+  if (letter) key = letter;
   else if (/^Digit\d$/.test(e.code)) key = e.code.slice(5);
   else if (/^Numpad\d$/.test(e.code)) key = e.code.slice(6);
   else if (/^F\d{1,2}$/.test(e.code)) key = e.code;