Add quick-win features: copy-on-select, middle-click paste, visual bell, zoom pane, clickable URLs, draggable dividers

- Copy on select: Auto-copy selected text to clipboard
- Middle-click paste: Quick paste with middle mouse button
- Visual bell: Subtle flash when commands complete
- Zoom pane: Cmd+Shift+Enter to maximize/restore split pane
- Clickable URLs: Cmd+click to open URLs in browser
- Draggable dividers: Resize split panes by dragging divider
- Updated help and keyboard shortcuts documentation

TerminalSession.swift

@@ -45,6 +45,32 @@ class TerminalSession: NSObject, NSTextViewDelegate, NSMenuDelegate {
         
         // Setup suggestion label
         setupSuggestionLabel()
+        
+        // Setup middle-click paste
+        setupMiddleClickPaste()
+        
+        // Setup clickable URLs
+        setupClickableURLs()
+    }
+    
+    private func setupMiddleClickPaste() {
+        let clickGesture = NSClickGestureRecognizer(target: self, action: #selector(handleMiddleClick(_:)))
+        clickGesture.buttonMask = 0x4 // Middle button
+        textView.addGestureRecognizer(clickGesture)
+    }
+    
+    @objc private func handleMiddleClick(_ gesture: NSClickGestureRecognizer) {
+        if let pasteString = NSPasteboard.general.string(forType: .string) {
+            textView.insertText(pasteString, replacementRange: textView.selectedRange())
+        }
+    }
+    
+    private func setupClickableURLs() {
+        textView.isAutomaticLinkDetectionEnabled = true
+        textView.linkTextAttributes = [
+            .foregroundColor: NSColor.systemBlue,
+            .underlineStyle: NSUnderlineStyle.single.rawValue
+        ]
     }
     
     private func setupContextMenu() {
@@ -362,6 +388,13 @@ class TerminalSession: NSObject, NSTextViewDelegate, NSMenuDelegate {
         if selectedRange.location < promptPosition && selectedRange.length == 0 {
             textView.setSelectedRange(NSRange(location: promptPosition, length: 0))
         }
+        
+        // Copy on select
+        if TerminalSettings.shared.copyOnSelect && selectedRange.length > 0 {
+            let selectedText = (textView.string as NSString).substring(with: selectedRange)
+            NSPasteboard.general.clearContents()
+            NSPasteboard.general.setString(selectedText, forType: .string)
+        }
     }
     
     private func getCurrentCommand() -> String {
@@ -555,12 +588,34 @@ class TerminalSession: NSObject, NSTextViewDelegate, NSMenuDelegate {
             }
         }
         
+        // Visual bell on command completion
+        if TerminalSettings.shared.visualBell {
+            DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { [weak self] in
+                self?.flashVisualBell()
+            }
+        }
+        
         // Show prompt after a delay
         DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
             self?.showPrompt()
         }
     }
     
+    private func flashVisualBell() {
+        guard let layer = textView.layer else { return }
+        let originalBg = layer.backgroundColor
+        
+        NSAnimationContext.runAnimationGroup({ context in
+            context.duration = 0.1
+            layer.backgroundColor = NSColor.white.withAlphaComponent(0.1).cgColor
+        }, completionHandler: {
+            NSAnimationContext.runAnimationGroup({ context in
+                context.duration = 0.2
+                layer.backgroundColor = originalBg
+            })
+        })
+    }
+    
     private func showHelp() {
         appendText("""
         Enhanced Terminal Commands: