Add ollie_goto_file and ollie_goto_symbol to the built-in radial's 'More'
branch, next to the command-palette escape hatch (panel-opening switchers
belong there, not the in-place top ring). onRadialActivated already
resolves both ids. Example config + a builtinDefaultHasLauncherSlices
test updated.
RadialConfig::load() reads $XDG_CONFIG_HOME/olliepalette/radials.json
when present and non-empty, else builtinDefault(); a broken/empty file
also falls back so the user is never left without radials. Add
userConfigPath() and loadFile(path,&error). setupRadials() now calls
load(). Example at docs/radials.example.json. 4 new tests.