POST /config/update stored keys the config file owns and answered 200
while the file silently kept winning. Run the config-owned check for
general_settings, litellm_settings, and router_settings before the first
database read, the way /config/field/update already does, so a refused
request stores nothing.
The config reload re-loaded the merged settings as yaml settings, which
turned every saved router setting read-only after one tick. Read the
saved router settings row instead so database-owned values stay writable.
The integration harness seeds num_retries through /config/update instead
of the config file, which is what the effective-settings and observed
routing tests need to keep exercising a database-owned value.
