e1608: probe and docs for the network scan

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

docs/claude/build-and-run.md

@@ -122,7 +122,8 @@ is exported when the option is absent, so GTK's own choice stands.
 drops the default**: only a run with no `aiN` key gets `ai0=BIP10V`, so `ai1=BIP5V` alone is channel 1
 alone, and a value that is not a range name is a channel that is off), `dir0`..`dir7` `i|o`,
 `plot0`..`plot7`, `plot_counter`, `do_init`, `ao0_init`, `ao1_init`). Either `address` or `mac` is
-required; a MAC with no `address` is looked up by broadcast, or by a sweep of `subnet` (`a.b.c`).
+required; a MAC with no `address` is looked up by a broadcast sent on every interface (`Scan`), or by a sweep of
+`subnet` (`a.b.c`).
 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`