docs: document xterm-ghostty terminfo fix for sudo (#146)

* docs: document xterm-ghostty terminfo fix for sudo

* docs: move troubleshooting content to TROUBLESHOOTING.md

---------

Co-authored-by: Dino Korah <691011+codemedic@users.noreply.github.com>

Author: codemedic

README.md

@@ -153,6 +153,10 @@ Since AppImages are self-contained executables, there is no formal installation
 
 </details>
 
+## 🛠️ Troubleshooting
+
+See [TROUBLESHOOTING.md](TROUBLESHOOTING.md) for known issues and fixes.
+
 ## 🤝 Contributing
 
 Contributions & Bugfixes are welcome. If you like to contribute, please feel free to fork the repository and submit a pull request.

TROUBLESHOOTING.md

@@ -0,0 +1,30 @@
+# Troubleshooting
+
+## `Error opening terminal: xterm-ghostty` when using `sudo`
+
+Ghostty sets `TERM=xterm-ghostty`, but the terminfo entry is bundled inside the AppImage and is not installed on the host system. When you run a terminal application via `sudo` (e.g., `sudo aptitude`, `sudo vim`), the root environment cannot find the terminfo entry and fails with:
+
+```
+Error opening terminal: xterm-ghostty.
+```
+
+**Fix:** extract the terminfo entry from the AppImage and install it system-wide.
+
+```bash
+# Extract the terminfo entry into a temporary directory
+tmpdir=$(mktemp -d /tmp/ghostty-appimage.XXXXXX)
+(cd "$tmpdir" && /path/to/Ghostty.AppImage --appimage-extract share/terminfo/x/xterm-ghostty)
+
+# Install for the current user
+mkdir -p ~/.local/share/terminfo/x
+cp "$tmpdir/squashfs-root/share/terminfo/x/xterm-ghostty" ~/.local/share/terminfo/x/
+
+# Install system-wide so root and sudo can find it
+sudo mkdir -p /usr/share/terminfo/x
+sudo cp "$tmpdir/squashfs-root/share/terminfo/x/xterm-ghostty" /usr/share/terminfo/x/
+
+# Clean up
+rm -rf "$tmpdir"
+```
+
+This only needs to be done once, or again after upgrading to a new AppImage release.