e1608: a configurable generator update rate, and the achieved rate in the Analog out panel

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

docs/claude/build-and-run.md

@@ -118,7 +118,7 @@ is exported when the option is absent, so GTK's own choice stands.
 `--source e1608` selects the MCC E-1608 Ethernet DAQ; its settings are `--source-opt` keys, all optional
 (`address` or `mac`+`subnet`, `port` 54211, `code` 0, `timeout_ms` 2000, `scan_rate` 1000 per channel,
 `ext_clock`, `trigger` `none|rising|falling|high|low`, `auto_restart` 1, `calibrate` 1, `poll_rate` 10,
-`mode` `se|diff`, `ai0`..`ai7` `BIP10V|BIP5V|BIP2V|BIP1V` (an absent key = off, **and any `aiN` key at all
+`gen_rate` 50 (Hz, 1 to 200: the waveform generator's DAC update rate), `mode` `se|diff`, `ai0`..`ai7` `BIP10V|BIP5V|BIP2V|BIP1V` (an absent key = off, **and any `aiN` key at all
 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