The context-menu key from ImGui, Silk.NET, GLFW and SDL ("Menu") is read as Alt, so Shift+Menu is stored as Alt+Shift and clashes with Alt bindings #222

What's wrong

CanonicalizeKey in Keybinding/Models/MusicalTypes.cs (around line 87 at 89f14b9) folds the bare name MENU to ALT:

"OPTION" or "MENU" or "LMENU" or "RMENU" or ... => "ALT",

In Win32 and WinForms, Menu does mean Alt (VK_MENU, Keys.Menu). The frameworks that #209 set out to support use the name for a different key: GLFW_KEY_MENU, Silk.NET Key.Menu, ImGuiKey.Menu and SDL SDLK_MENU are the application / context-menu key. A host that passes key.ToString() from any of these, as #209's folding invites, gets Alt for the menu key without any warning.

Failure scenario

Chord.Parse("Menu")                                   = Alt   (equals Alt: True)
bind "context.menu" to Shift+Menu  → stored chord     = Alt+Shift
bind "menu.bar" to Shift+Alt       → context.menu loses its chord (displaced)
press Shift+Menu                   → executes menu.bar

The user's context-menu binding silently merges with the Alt modifier. Binding Alt+Shift elsewhere removes it, and pressing the menu key runs the Alt command.

This is a name collision between frameworks, not a typo. The WinForms mapping is intentional and tested in Keybinding.Test/KeyAliasEquivalenceTests.cs:40, [DataRow("Menu+A", "Alt+A")], and comes from #166. Those two uses of the name can't both be served by one global alias.

Suggested fix

• Keep LMENU/RMENU → ALT, since those are unambiguous, but stop folding the bare MENU, so it stays a key of its own. Add a comment explaining why.
• WinForms hosts already have to map Keys.Menu from a KeyEventArgs, where e.Alt is also available. If WinForms support for the bare name matters, document it, or offer an opt-in framework alias table instead of a global fold.
• Update the Menu+A test row to match whichever behaviour is chosen.

Acceptance criteria:

• Chord.Parse("Shift+Menu") is not equal to Alt+Shift.
• Binding Shift+Alt doesn't displace a Shift+Menu binding.
• LMenu+A / RMenu+A still compare equal to Alt+A.