example.dbc name confusion

[haoruizhou]

The Docker Compose setup currently mounts any user-provided DBC file into the container as example.dbc. Because the repo also ships with an actual example.dbc, the startup-data-loader logs can look misleading. Users may think their own DBC wasn’t loaded correctly when it actually was.

Problem
• The container always sees the mounted DBC as example.dbc.
• The repo includes a real example.dbc for reference.
• In the logs, both appear identical, so it’s hard to tell whether the loader is using the built-in example or the user’s file.
• This can cause unnecessary debugging and confusion.

Proposed fix
• Allow the mounted DBC to retain its original filename, or
• Mount it as something like uploaded.dbc, or
• Add clearer logging indicating which file was loaded.