docker: bootstrap config on startup and include rootless container fixes

[yellowcooln]

Had old repo path, Changing to

pyMC-dev/pyMC_Repeater

[yellowcooln]

• Docker now behaves more like a normal upgraded install instead of a one-time bootstrap.

• On container startup:

  • If config.yaml is missing or empty, it is created from config.yaml.example
  • If config.yaml already exists, it is merged with the latest example config using the same yq strategy as the normal upgrader

• Merge behavior:

  • Existing user settings remain intact
  • Newly introduced config options are added automatically
  • Comments come from the example config, so the file stays clean instead of accumulating duplicated comment blocks over time

• This keeps Docker users current with new config fields without overwriting their existing setup

• The branch also includes the rootless Docker fixes from bplein’s upstream PR Updates to dockerfile for rootless container #248:

  • Updates to dockerfile for rootless container #248

• Container builds and runs as the unprivileged repeater user instead of root