Force English locale for GPG verify to fix localized output parsing

Root cause: GPG outputs verification messages in the user's locale
(e.g., German "Gute Signatur von" instead of "Good signature from"),
causing the parsing logic to fail and display "Unknown signer".

Solution: Force LC_ALL=C and LANG=C environment variables when
calling 'gpg --verify' to ensure consistent English output across
all locales.

This ensures the code can reliably parse "Good signature from"
regardless of the user's system language settings.

trace/crypto.py

@@ -43,12 +43,19 @@ class Crypto:
             return False, "Not a GPG signed message"
 
         try:
+            # Force English output for consistent parsing across locales
+            import os
+            env = os.environ.copy()
+            env['LC_ALL'] = 'C'
+            env['LANG'] = 'C'
+
             proc = subprocess.Popen(
                 ['gpg', '--verify'],
                 stdin=subprocess.PIPE,
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE,
-                text=True
+                text=True,
+                env=env
             )
             stdout, stderr = proc.communicate(input=signed_content, timeout=10)