utils/library_location.py decides where the library lives: the
PROMPT_MANAGER_DATA_DIR folder (validated: absolute, never inside a folder
ComfyUI or Prompt Manager serves), an explicit database.default_path as
before, a node-folder library that was not moved, else ComfyUI's
user/__promptmanager. The database, diagnostics, config.json, logs and the
LoRA image cache all ask it, so a new install never writes into the node
folder and an existing one keeps every path until the user moves it.
"Keep it here" is persisted as library.keep_in_node_folder.
