Add command history navigation with up/down arrows

- Up arrow: Navigate to previous commands in history
- Down arrow: Navigate to next commands (or back to current input)
- Works exactly like standard terminal behavior
- Preserves current input when starting navigation
- Resets on command execution

TerminalSession.swift

@@ -12,6 +12,9 @@ class TerminalSession: NSObject, NSTextViewDelegate, NSMenuDelegate {
     var title: String
     var currentWorkingDirectory: String = "~"
     private var currentSuggestion: String?
+    private var historyIndex: Int = -1
+    private var historyBuffer: [String] = []
+    private var currentInput: String = ""
     
     init(title: String = "Terminal") {
         self.sessionID = UUID()
@@ -232,6 +235,80 @@ class TerminalSession: NSObject, NSTextViewDelegate, NSMenuDelegate {
         return cleaned
     }
     
+    func textView(_ textView: NSTextView, doCommandBy commandSelector: Selector) -> Bool {
+        // Handle up arrow - previous command in history
+        if commandSelector == #selector(NSResponder.moveUp(_:)) {
+            navigateHistory(direction: .previous)
+            return true
+        }
+        
+        // Handle down arrow - next command in history
+        if commandSelector == #selector(NSResponder.moveDown(_:)) {
+            navigateHistory(direction: .next)
+            return true
+        }
+        
+        return false
+    }
+    
+    private enum HistoryDirection {
+        case previous, next
+    }
+    
+    private func navigateHistory(direction: HistoryDirection) {
+        // Load history if not already loaded
+        if historyBuffer.isEmpty {
+            historyBuffer = HistoryManager.shared.getRecentCommands(100)
+        }
+        
+        guard !historyBuffer.isEmpty else { return }
+        
+        // Save current input if we're starting to navigate
+        if historyIndex == -1 {
+            currentInput = getCurrentCommand()
+        }
+        
+        // Navigate history
+        switch direction {
+        case .previous:
+            if historyIndex < historyBuffer.count - 1 {
+                historyIndex += 1
+            }
+        case .next:
+            if historyIndex > -1 {
+                historyIndex -= 1
+            }
+        }
+        
+        // Update command line
+        let newCommand: String
+        if historyIndex == -1 {
+            // Back to original input
+            newCommand = currentInput
+        } else {
+            // Show history command
+            newCommand = historyBuffer[historyIndex]
+        }
+        
+        // Replace current command with history command
+        replaceCurrentCommand(with: newCommand)
+    }
+    
+    private func replaceCurrentCommand(with newCommand: String) {
+        let currentLength = textView.string.count
+        let commandLength = currentLength - promptPosition
+        
+        if commandLength > 0 {
+            let range = NSRange(location: promptPosition, length: commandLength)
+            textView.textStorage?.replaceCharacters(in: range, with: newCommand)
+        } else {
+            textView.insertText(newCommand, replacementRange: NSRange(location: promptPosition, length: 0))
+        }
+        
+        // Move cursor to end
+        textView.setSelectedRange(NSRange(location: textView.string.count, length: 0))
+    }
+    
     func textView(_ textView: NSTextView, shouldChangeTextIn range: NSRange, replacementString: String?) -> Bool {
         // Don't allow editing before the prompt
         if range.location < promptPosition {
@@ -402,6 +479,11 @@ class TerminalSession: NSObject, NSTextViewDelegate, NSMenuDelegate {
         
         let trimmed = command.trimmingCharacters(in: .whitespacesAndNewlines)
         
+        // Reset history navigation
+        historyIndex = -1
+        currentInput = ""
+        historyBuffer = []  // Reload on next navigation
+        
         // Check for aliases - match the first word
         var actualCommand = trimmed
         let components = trimmed.split(separator: " ", maxSplits: 1)