Fix Cmd+K conflict and add custom app icon

- Changed AI Generator shortcut from Cmd+K to Cmd+I
- Cmd+K now only triggers Clear Screen
- Created custom terminal-style app icon with Python/PIL
- Updated build script to include icon in app bundle
- Updated all documentation with correct shortcuts
- New DMG with icon included (492K)

EnhancedTerminal.app/Contents/Info.plist

@@ -6,6 +6,8 @@
     <string>en</string>
     <key>CFBundleExecutable</key>
     <string>EnhancedTerminal</string>
+    <key>CFBundleIconFile</key>
+    <string>AppIcon</string>
     <key>CFBundleIdentifier</key>
     <string>com.enhanced.terminal</string>
     <key>CFBundleInfoDictionaryVersion</key>