Rename native borderRadius prop to avoid UIView collision

RN/Expo already owns a borderRadius property on UIView (as a style prop),
so declaring `private var borderRadius` on ExpoView was rejected by Swift
("cannot override with a stored property"). Rename the bridge prop and Swift
property to `previewCornerRadius`; the public Trigger/ImageContextMenu API
keeps `borderRadius` and Root translates it at the bridge layer.

Also tighten `var start` to `let` in the SVG parser.

https://claude.ai/code/session_015REmux3R9uuEMMJUHxTyQT

modules/expo-bluesky-context-menu/ios/ExpoBlueskyContextMenuView.swift

@@ -2,21 +2,20 @@ import ExpoModulesCore
 import UIKit
 
 /// Native view that hosts the children and attaches a
-/// `UIContextMenuInteraction`. Two JS-shipped props drive behaviour:
-/// - `preview`:  discriminated union describing what to show during peek
+/// `UIContextMenuInteraction`. JS-shipped props drive behaviour:
+/// - `preview`: discriminated union describing what to show during peek
 /// - `menuItems`: array of menu item specs (see `MenuBuilder`)
-/// - `borderRadius`: used for the targeted preview's visible path so the lift
-///   animation matches the thumbnail's clipping
+/// - `previewCornerRadius`: used for the targeted preview's visible path so the
+///   lift animation matches the thumbnail's clipping. (Named distinctly from
+///   the RN-owned `borderRadius` style prop on UIView.)
 class ExpoBlueskyContextMenuView: ExpoView, UIContextMenuInteractionDelegate {
   private var preview: [String: Any]?
   private var menuItems: [[String: Any]] = []
-  private var borderRadius: CGFloat = 0
+  private var previewCornerRadius: CGFloat = 0
 
   private let onItemPress = EventDispatcher()
   private let onPreviewPress = EventDispatcher()
 
-  private var pendingCommitId: String?
-
   required init(appContext: AppContext? = nil) {
     super.init(appContext: appContext)
     let interaction = UIContextMenuInteraction(delegate: self)
@@ -25,7 +24,9 @@ class ExpoBlueskyContextMenuView: ExpoView, UIContextMenuInteractionDelegate {
 
   func setPreview(_ value: [String: Any]?) { self.preview = value }
   func setMenuItems(_ value: [[String: Any]]) { self.menuItems = value }
-  func setBorderRadius(_ value: Double) { self.borderRadius = CGFloat(value) }
+  func setPreviewCornerRadius(_ value: Double) {
+    self.previewCornerRadius = CGFloat(value)
+  }
 
   // MARK: - UIContextMenuInteractionDelegate
 
@@ -83,10 +84,10 @@ class ExpoBlueskyContextMenuView: ExpoView, UIContextMenuInteractionDelegate {
   private func makeTargetedPreview() -> UITargetedPreview {
     let parameters = UIPreviewParameters()
     parameters.backgroundColor = .clear
-    if borderRadius > 0 {
+    if previewCornerRadius > 0 {
       parameters.visiblePath = UIBezierPath(
         roundedRect: self.bounds,
-        cornerRadius: borderRadius
+        cornerRadius: previewCornerRadius
       )
     }
     return UITargetedPreview(view: self, parameters: parameters)