Fix synchronous PI based on testing/feedback

[sethbern]

Fixed several sync PI issues from testing feedback:

• Show real student names in the verbal group select dropdown instead of anonymous names
• Fixed premature "discuss" message after vote 1 stops
• Added line numbers to code blocks displayed in PI questions (does not touch the actual questions, just adds them visually during a PI session based on instructor feedback that it makes discussion easier)
• Improved group select placeholder text

Also, some PI pages still seem to route to web2py instead of FastAPI. I think it's because nginx serves /staticAssets/ from the web2py static directory, but if it's something else on my end let me know and I can fix it.