Plugin packages need somewhere to keep their own settings, but MVT
rewrites its config.yaml with only the fields it knows about, so any
foreign section is dropped. Add MVTPluginSettings, a pydantic-settings
base class that gives each plugin its own file under the MVT config
folder and its own MVT_PLUGIN_<NAME>_ environment variable namespace.
Settings resolve from constructor arguments, then the environment, then
the plugin file, then the field defaults. Saving skips the values the
environment currently supplies, so credentials passed as environment
variables are not copied to disk, and writes through a private temporary
file so a settings file is never partially written or briefly readable
by other users.
The Development section holds more than one page and will grow further,
so give it its own directory. development.md becomes development/index.md,
which keeps its published URL, and the custom CLI command page moves
alongside it.
Update the nav, the cross-link between the two pages, and the README
link to the custom command documentation, which is now published at
/development/custom_commands/.
Donncha Ó Cearbhaill