docs: reconcile the E-1608 README with the real-board run and the scan lookup

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/claude/build-and-run.md

@@ -127,8 +127,8 @@ required; a MAC with no `address` is looked up by a broadcast sent on every inte
 The enabled channels times `scan_rate` must not exceed 250 kS/s. `tools/mock_e1608.py` is a protocol
 mock of the board for development (UDP discovery and handshake, TCP commands, a scan stream with a sine
 per channel, calibration memory, `--port`, `--mac`, `--log FILE`, `--drop-after S` and `--overrun-after S`
-switches, `--code N`); there is no real board in the loop, and the mock's header lists the items whose
-layout is unverified. Errors are written to stderr as `[e1608] ...`, once per distinct message.
+switches, `--code N`); the mock stands in for the board (a real board has been run once, with one channel; see
+the README), and the mock's header lists the items whose layout is unverified. Errors are written to stderr as `[e1608] ...`, once per distinct message.
 
 ```sh
 python3 tools/mock_e1608.py --port 54711 &