Keep an operator's windows, colours and recordings

Ctrl+O asks who is at the radio, as it does in N1MM, and the callsign goes on
every contact logged from then on. A multi-operator station changes hands every
few hours, so each operator also keeps what he wants the program to look like:
where the windows sit, the theme, and the folder his recordings are in.

The windows on the screen are stored against the operator leaving, before the
dialog opens, and the operator taking over gets his own back. A window he opens
later is placed as it appears. An operator who is new to the list starts with
whatever is on the screen.

Nothing plays the recordings yet, so the folder is stored and waits on voice
keying. {OPERATOR} in a message sends the callsign.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RoGtneMQaz4M9w7Kk49AVD

README.md

@@ -400,6 +400,29 @@ to a tenth of a degree: `src/Nonemm.App/Assets/coastline.txt`. The sun's
 position is the standard low-precision solar formula, good to about a hundredth
 of a degree.
 
+### Operators
+
+**Ctrl+O**, or **Config → Change Operator…**, asks who is at the radio. The
+callsign goes on every contact logged from then on, in the log's Op column and
+in the ADIF `OPERATOR` field, and `{OPERATOR}` in a message sends it.
+
+Each operator keeps three things of his own, which is what makes the key worth
+pressing at a multi-operator station:
+
+| Kept | What happens on the way in and out |
+|---|---|
+| Window positions | where every open window sits is stored against the operator leaving, and the operator taking over gets his own back. A window opened later is placed as it appears |
+| Colours | the theme he last had |
+| Recordings folder | the folder his wav files are in, since a voice keyer plays the recordings of whoever is at the microphone |
+
+An operator whose callsign is not in the list is made by typing it, and starts
+with the windows and colours on the screen. **Remove** drops one from the list;
+the contacts he logged keep his callsign, because those are in the log rather
+than in the settings.
+
+Nothing plays the recordings yet — there is no voice keyer — so the folder is
+stored and passed on rather than used.
+
 ### The log window
 
 The pane under the log lists what has already been worked with the call being