fix: Code review fixes for multiple Python files

Fixed the following issues:

1. gitstatus.py:
   - Fixed broad IOError exception handling to catch specific OSError/FileNotFoundError
   - Fixed unused variable warning by using _ for ignored stderr

2. proxy.py:
   - Fixed os.path.expandvars usage that doesn't expand ~, changed to os.path.expanduser
   - Fixed check_output call that was incorrectly passing a file path instead of command list
   - Fixed missing space in env variable assignment for aliases

3. update_emoji.py:
   - Fixed file handle leaks by using with statements for file operations
   - Removed unnecessary .keys() call in dict iteration

4. cheatsheet.py:
   - Fixed parse() function to handle lines without '=' character
   - Fixed inefficient list comprehension using any() instead
   - Fixed shadowing of built-in 'cheatsheet' function name

5. ssh-agent.py:
   - Modernized string formatting from .format() to f-string

6. ssh-proxy.py:
   - Fixed next() call without default value that crashes when no proxy env vars set
   - Fixed missing exit code propagation from subprocess.call

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

plugins/shell-proxy/ssh-agent.py

@@ -8,7 +8,7 @@ ssh_proxy = os.path.join(os.path.dirname(__file__), "ssh-proxy.py")
 argv = [
     os.environ.get("__SSH_PROGRAM_NAME__", "ssh"),
     "-o",
-    "ProxyCommand={} %h %p".format(ssh_proxy),
+    f"ProxyCommand={ssh_proxy} %h %p",
     "-o",
     "Compression=yes",
 ]