style(share-ext): clean SF-Symbol X + paper-plane instead of heavy pill/circle

The top-bar buttons looked heavy against the navy bar (thick grey X-circle, bold
"Send" pill). Swapped for light SF Symbols on the navy bar: a thin `xmark` for
cancel and a `paperplane.fill` for send (semibold, enables when ≥1 chat is picked).
Icon-only send matches the Teams reference — the radio checks already show what's
selected, so the "(N)" count text is dropped. Native-only — needs a build.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

mobile/ios-share/ShareViewController.swift

@@ -89,8 +89,11 @@ class ShareViewController: UIViewController, UITableViewDataSource, UITableViewD
         nav.scrollEdgeAppearance = appearance
         nav.tintColor = .white
         let navItem = UINavigationItem(title: "Share to Biz Connect")
-        navItem.leftBarButtonItem = UIBarButtonItem(barButtonSystemItem: .cancel, target: self, action: #selector(cancelTapped))
-        sendButton = UIBarButtonItem(title: "Send", style: .done, target: self, action: #selector(sendTapped))
+        // Clean, light SF Symbols instead of a heavy grey X-circle / bold pill (thin xmark + paper-plane).
+        let symCfg = UIImage.SymbolConfiguration(pointSize: 16, weight: .regular)
+        navItem.leftBarButtonItem = UIBarButtonItem(image: UIImage(systemName: "xmark", withConfiguration: symCfg), style: .plain, target: self, action: #selector(cancelTapped))
+        let sendCfg = UIImage.SymbolConfiguration(pointSize: 18, weight: .semibold)
+        sendButton = UIBarButtonItem(image: UIImage(systemName: "paperplane.fill", withConfiguration: sendCfg), style: .plain, target: self, action: #selector(sendTapped))
         sendButton.isEnabled = false
         navItem.rightBarButtonItem = sendButton
         nav.setItems([navItem], animated: false)
@@ -172,9 +175,8 @@ class ShareViewController: UIViewController, UITableViewDataSource, UITableViewD
     }
 
     private func updateSendButton() {
-        let n = selected.count
-        sendButton.title = n > 0 ? "Send (\(n))" : "Send"
-        sendButton.isEnabled = n > 0 && !sending
+        // Icon-only paper-plane (like Teams); the radio checks show what's selected. Just enable/disable.
+        sendButton.isEnabled = !selected.isEmpty && !sending
     }
 
     // MARK: - Preview thumbnails