Add a manual page, and explain every setting in plain words

Every setting now carries a paragraph saying what it is in everyday terms
and why someone who does not already speak radio would turn it up, down,
on or off: what the squelch knob actually is, why automatic gain is a bad
idea for scanning, why a bias tee can damage equipment, why setting the
transcription language matters on noisy audio. The menus and
`config --describe` show it alongside the existing technical detail.

packaging/make-man.py generates bandsaunter(1) from that same table, so the
manual cannot document a setting the program lacks or miss one it has --
tests check both, that the page renders through groff without a single
warning, and that the guidance survives into the rendered output. Around
it are hand-written sections on the commands, entering frequencies, the
band plan, lock-outs, the keys during a scan, HF, single sideband, files,
environment variables and worked examples.

The .deb regenerates and installs it rather than shipping a copy, so an
installed manual always matches the installed program.

The README picks up what the last few commits added: the plain display as
a saved setting, what the settings tests now guarantee, and where to read
the manual before installing.

Version is the day's build: 2026-08-22_01.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -296,6 +296,16 @@ bandsaunter scan -p local
 bandsaunter profiles
 ```
 
+Everything that can be given as a flag can be saved, and everything that can be
+saved can be given as a flag — both front ends are generated from one table, so
+they cannot drift apart. A profile written by an older version still loads: keys
+it does not have take their defaults, and keys that no longer exist are reported
+and ignored.
+
+Every setting is explained in plain language — what it is, and when you would
+change it — in three places: `bandsaunter config --describe <name>`, `?N` in the
+settings menu, and `man bandsaunter`.
+
 ## Entering frequencies
 
 **By hand** — repeat `-r` as many times as you like; there is no limit on the
@@ -826,6 +836,11 @@ since that is the command to run when something is wrong, and
 | `l` | lock out this frequency — for this run and every later one |
 | `+` / `-` | adjust the squelch threshold |
 
+There is no live display over ssh, in a log file, or piped to another program:
+`--plain` prints one line per recording instead, and is chosen automatically
+whenever output is not a terminal. It is a saved setting like any other, so a
+headless machine can be told once and never asked again.
+
 ### Lock-outs
 
 A pager transmitter down the road, or a birdie the receiver makes itself, is
@@ -858,6 +873,23 @@ there explains that setting instead.
 From the command line, `bandsaunter config --describe <setting>` does the same,
 and `bandsaunter scan --help` lists every flag grouped the same way as the menus.
 
+### The manual page
+
+`man bandsaunter` documents every command, option and setting, each with a
+plain-language note on what it is and why you would turn it up, down, on or
+off — written for someone who does not already speak radio.
+
+It is generated from the same settings table the menus and the flags come from,
+so it cannot describe a setting the program does not have, or miss one it does:
+
+```bash
+./packaging/make-man.py           # regenerate packaging/bandsaunter.1
+man -l packaging/bandsaunter.1    # read it without installing
+```
+
+The `.deb` installs it; installing from source does not, so read it from the
+source tree with `man -l`.
+
 ## HF
 
 Frequencies below 24 MHz need direct sampling, which most RTL-SDR dongles
@@ -911,7 +943,19 @@ audio, IQ and metadata are correct.
 The simulator's voice transmitters carry synthesised speech -- glottal pulses
 through moving formants, compressed the way a real transmitter compresses,
 then gated into syllables and phrases -- because sine tones would not exercise
-the speech detector at all.
+the speech detector at all. SSB transmitters are filtered to their audio
+passband first, since that filter is what makes a signal single-sideband, and
+without it the simulated signal was several times wider than anything on the
+air.
+
+Its transmitters seed themselves deterministically, so a test that fails can be
+made to fail again -- the one thing needed to fix it.
+
+Settings have their own tests: every one is set to something other than its
+default, saved, loaded back and compared, so nothing can quietly fail to
+persist. Every setting must also be reachable from both the command line and
+the menus, be read somewhere in the program, display a value that can be typed
+straight back in, and appear in the manual page.
 
 ## Legal note