XENG-10487 Fix VCS detection failure exit code

sys.exit() without argument exits 0 (success). Both VCSUnsupported and
VCSMissingRevision errors now exit with code 1 to signal failure.

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

Author: saville

buildrunner/__init__.py

@@ -115,10 +115,10 @@ def __init__(
             self.log.write(
                 f"{err}\nPlease verify you have a VCS set up for this project.\n"
             )
-            sys.exit()
+            sys.exit(1)
         except VCSMissingRevision as err:
             self.log.write(f"{err}\nMake sure you have at least one commit.\n")
-            sys.exit()
+            sys.exit(1)
 
         # load global configuration - must come *after* VCS detection
         BuildRunnerConfig.initialize_instance(