Finishes 3b14431 (which only captured the file renames): apply the
identifier/endpoint/env/UI changes so the code matches the new paths
— PModule/PController/PSourceDbService, @Controller("p"), /p/oem,
config key `p`, P_DB_ENABLED/P_DB_URL, "P kataloğundan…" copy.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>