Add menu positioning and accelerator APIs

Introduces Placement and PositioningStrategy types for flexible menu positioning, moving Placement to its own file. Adds keyboard accelerator support to MenuItem, including AcceleratorModifiers and KeyboardAccelerator types. Enhances Menu with item accessors and positioning options, and TrayIcon with contextMenuTrigger property and improved context menu control. Updates Package.swift platform exclusions and CNativeAPI submodule.

Author: lijy91

Package.swift

@@ -26,8 +26,11 @@ let package = Package(
             exclude: {
                 var excluded = [
                     "examples",
+                    "src/platform/android",
+                    "src/platform/ios",
                     "src/platform/linux",
                     "src/platform/macos",
+                    "src/platform/ohos",
                     "src/platform/windows",
                 ]
                 #if os(Linux)

Sources/CNativeAPI

@@ -111,91 +111,3 @@ public struct Offset: Equatable, Hashable, Sendable {
     }
 }
 
-/// Placement options for positioning UI elements relative to an anchor.
-///
-/// Placement defines how a UI element (such as a menu or popover) should be
-/// positioned relative to a reference point or rectangle.
-///
-/// Example:
-/// ```swift
-/// // Position menu below the anchor, horizontally centered
-/// menu.open(strategy, placement: .bottom)
-///
-/// // Position menu below the anchor, aligned to the left
-/// menu.open(strategy, placement: .bottomStart)
-///
-/// // Position menu above the anchor, aligned to the right
-/// menu.open(strategy, placement: .topEnd)
-/// ```
-public enum Placement: Int32, CaseIterable {
-    /// Position above the anchor, horizontally centered.
-    case top = 0
-    
-    /// Position above the anchor, aligned to the start (left).
-    case topStart = 1
-    
-    /// Position above the anchor, aligned to the end (right).
-    case topEnd = 2
-    
-    /// Position to the right of the anchor, vertically centered.
-    case right = 3
-    
-    /// Position to the right of the anchor, aligned to the start (top).
-    case rightStart = 4
-    
-    /// Position to the right of the anchor, aligned to the end (bottom).
-    case rightEnd = 5
-    
-    /// Position below the anchor, horizontally centered.
-    case bottom = 6
-    
-    /// Position below the anchor, aligned to the start (left).
-    case bottomStart = 7
-    
-    /// Position below the anchor, aligned to the end (right).
-    case bottomEnd = 8
-    
-    /// Position to the left of the anchor, vertically centered.
-    case left = 9
-    
-    /// Position to the left of the anchor, aligned to the start (top).
-    case leftStart = 10
-    
-    /// Position to the left of the anchor, aligned to the end (bottom).
-    case leftEnd = 11
-    
-    internal var nativeValue: native_placement_t {
-        switch self {
-        case .top: return NATIVE_PLACEMENT_TOP
-        case .topStart: return NATIVE_PLACEMENT_TOP_START
-        case .topEnd: return NATIVE_PLACEMENT_TOP_END
-        case .right: return NATIVE_PLACEMENT_RIGHT
-        case .rightStart: return NATIVE_PLACEMENT_RIGHT_START
-        case .rightEnd: return NATIVE_PLACEMENT_RIGHT_END
-        case .bottom: return NATIVE_PLACEMENT_BOTTOM
-        case .bottomStart: return NATIVE_PLACEMENT_BOTTOM_START
-        case .bottomEnd: return NATIVE_PLACEMENT_BOTTOM_END
-        case .left: return NATIVE_PLACEMENT_LEFT
-        case .leftStart: return NATIVE_PLACEMENT_LEFT_START
-        case .leftEnd: return NATIVE_PLACEMENT_LEFT_END
-        }
-    }
-    
-    internal init(nativeValue: native_placement_t) {
-        switch nativeValue {
-        case NATIVE_PLACEMENT_TOP: self = .top
-        case NATIVE_PLACEMENT_TOP_START: self = .topStart
-        case NATIVE_PLACEMENT_TOP_END: self = .topEnd
-        case NATIVE_PLACEMENT_RIGHT: self = .right
-        case NATIVE_PLACEMENT_RIGHT_START: self = .rightStart
-        case NATIVE_PLACEMENT_RIGHT_END: self = .rightEnd
-        case NATIVE_PLACEMENT_BOTTOM: self = .bottom
-        case NATIVE_PLACEMENT_BOTTOM_START: self = .bottomStart
-        case NATIVE_PLACEMENT_BOTTOM_END: self = .bottomEnd
-        case NATIVE_PLACEMENT_LEFT: self = .left
-        case NATIVE_PLACEMENT_LEFT_START: self = .leftStart
-        case NATIVE_PLACEMENT_LEFT_END: self = .leftEnd
-        default: self = .bottomStart
-        }
-    }
-}