fix(grid-agent): move setup into YAML preferences (#135)

docs/grid-agent-tui.md

@@ -8,21 +8,29 @@ Run an embedded UI with a live-grid integrated configuration:
 
 ```sh
 cargo run --locked -p metacrate-grid-agent --features live-grid -- \
-  --config config/grid-agent.json --tui
+  --config config/grid-agent.integrated.example.yml --tui
 ```
 
 Run a separate UI against a loopback split service:
 
 ```sh
 cargo run --locked -p metacrate-grid-agent -- \
-  --config config/grid-agent.json --tui-client
+  --config config/grid-agent.split.example.yml --tui-client
 ```
 
-The split client reads its operator capability through the normal secret-file
-or environment configuration. It never displays or copies that value. Remote
+The split client reads its operator capability from the ACL-restricted
+`config.yml`. It never displays or copies that value. Remote
 TLS clients must embed `TuiTransport` with their explicitly configured trust
 roots; the command-line client intentionally accepts loopback TCP only.
 
+Open preferences before a service is configured with
+`metacrate-grid-agent --preferences`; the same panel is available from the live
+TUI. It edits the endpoint, optional model, grid identity, hidden credentials,
+mode, and privileged UUID list while preserving advanced YAML settings. Use
+Up/Down to select, Enter to edit/commit, `w` to save, and Esc to cancel. Changes
+to connection or authorization settings apply after restart. A one-time
+`--import-env /path/to/.env` migrates legacy `GRID_*` and `OPENAPI_*` values.
+
 Use Tab/arrow keys to change panels and scroll. `r` refreshes; `p`/`u` pause or
 resume; `f` reconnects the grid; `a`/`d` approve or deny the first pending
 approval; `x` cancels the newest visible action; `e` expires the first visible