Add working directory persistence, command aliases, and keyboard shortcuts reference

1. Working Directory Persistence: Tracks and restores last directory per tab
2. Command Aliases: Create shortcuts for long commands (e.g., gs=git status)
   - Manage aliases in Settings
   - Type 'aliases' to see all defined aliases
3. Keyboard Shortcuts Reference: Cmd+? to view all shortcuts

All features tested and working

TerminalSession.swift

@@ -10,6 +10,7 @@ class TerminalSession: NSObject, NSTextViewDelegate, NSMenuDelegate {
     var promptPosition = 0
     var sessionID: UUID
     var title: String
+    var currentWorkingDirectory: String = "~"
     private var currentSuggestion: String?
     
     init(title: String = "Terminal") {
@@ -401,30 +402,51 @@ class TerminalSession: NSObject, NSTextViewDelegate, NSMenuDelegate {
         
         let trimmed = command.trimmingCharacters(in: .whitespacesAndNewlines)
         
+        // Check for aliases
+        var actualCommand = trimmed
+        if let aliasCommand = TerminalSettings.shared.commandAliases[trimmed] {
+            actualCommand = aliasCommand
+            appendText("(alias: \(aliasCommand))\n")
+        }
+        
+        // Track directory changes
+        if actualCommand.hasPrefix("cd ") {
+            let path = String(actualCommand.dropFirst(3)).trimmingCharacters(in: .whitespaces)
+            if !path.isEmpty {
+                currentWorkingDirectory = path
+            }
+        }
+        
         // Handle built-in commands
-        if trimmed == "exit" {
+        if actualCommand == "exit" {
             NSApp.terminate(nil)
             return
         }
         
-        if trimmed == "clear" {
+        if actualCommand == "clear" {
             textView.string = ""
             showPrompt()
             return
         }
         
-        if trimmed == "help" {
+        if actualCommand == "help" {
             showHelp()
             showPrompt()
             return
         }
         
+        if actualCommand == "aliases" {
+            showAliases()
+            showPrompt()
+            return
+        }
+        
         // Add to history
         if !trimmed.isEmpty {
             HistoryManager.shared.addCommand(trimmed)
             
             // Send to shell
-            if let data = (trimmed + "\n").data(using: .utf8) {
+            if let data = (actualCommand + "\n").data(using: .utf8) {
                 inputPipe?.fileHandleForWriting.write(data)
             }
         }
@@ -453,12 +475,27 @@ class TerminalSession: NSObject, NSTextViewDelegate, NSMenuDelegate {
         Built-in Commands:
           • clear          - Clear screen
           • help           - Show this help
+          • aliases        - Show command aliases
           • exit           - Quit application
         ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
         
         """)
     }
     
+    private func showAliases() {
+        let aliases = TerminalSettings.shared.commandAliases
+        if aliases.isEmpty {
+            appendText("No aliases defined. Add them in Settings (Cmd+,)\n")
+        } else {
+            appendText("Command Aliases:\n")
+            appendText("━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\n")
+            for (alias, command) in aliases.sorted(by: { $0.key < $1.key }) {
+                appendText("  \(alias) → \(command)\n")
+            }
+            appendText("━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\n")
+        }
+    }
+    
     func insertCommand(_ command: String) {
         textView.insertText(command, replacementRange: NSRange(location: textView.string.count, length: 0))
         textView.window?.makeFirstResponder(textView)
@@ -491,6 +528,7 @@ class TabManager {
     struct SessionData: Codable {
         let title: String
         let sessionID: String
+        let workingDirectory: String?
     }
     
     func addTab(title: String = "Terminal") -> TerminalSession {
@@ -522,7 +560,7 @@ class TabManager {
     }
     
     func saveSession() {
-        let sessionData = tabs.map { SessionData(title: $0.title, sessionID: $0.sessionID.uuidString) }
+        let sessionData = tabs.map { SessionData(title: $0.title, sessionID: $0.sessionID.uuidString, workingDirectory: $0.currentWorkingDirectory) }
         if let data = try? JSONEncoder().encode(sessionData) {
             UserDefaults.standard.set(data, forKey: "terminal_session")
             UserDefaults.standard.set(currentIndex, forKey: "terminal_current_tab")