…#3445) (aethersdr#3555)

## Summary

Doc-only. Corrects two items the RadioSession v1 class doc (merged in
aethersdr#3544) listed as "v3 scope" that don't survive closer inspection. No
code change — captures a finding so neither gets attempted as written.

I went to build the **SessionSettings facade** (the documented next
step) and the investigation showed it's premature. Rather than build
speculative infrastructure with no consumer — the first such thing in
the 12-PR series — here's the finding, recorded in the class doc where
the next contributor will see it.

## Finding 1: the wire bodies can't move onto RadioSession

`wireDiscovery` / `wireRadioModel` / `wirePanLifecycle` are **~100
`connect()` calls with ~76 references to MainWindow's widgets** (applet
panel, title bar, pan stack, spectrum widgets, status bar). They're
application-layer model→UI glue. Moving them onto a `src/models/` class
would invert the dependency — RadioSession would have to `#include` the
GUI. They belong in the GUI layer (where they are now), full stop.

## Finding 2: the SessionSettings facade is premature

There is no per-radio AppSettings namespace to wrap. Per-radio state
today is:

| Category | Examples | Where it lives |
|---|---|---|
| Global | `StationName`, `LastConnectedRadioSerial` | flat AppSettings
(genuinely global — station is per-operator, last-serial is a reconnect
pointer) |
| Radio-side | slice/pan positions, modes | FlexRadio SSDR profiles
(`profile global info`) — see aethersdr#3384 |
| Already per-radio | band-stack entries |
`BandStackSettings::sanitizeSerial()` → `"Radio_<serial>"` keys |

**`BandStackSettings` is the one working per-radio-namespacing pattern
in the codebase** — it's the template multi-radio should follow when a
second session creates a real consumer. A facade built now would wrap
nothing and have no caller.

## What this means for the series

The aethersdr#3351 refactor is **complete**. The architecturally hard work — the
19,474→8,135-line decomposition and the by-value→session-collection
extraction (937 call sites) — is merged. RadioSession owns `{RadioModel,
TciServer, CatPort[8], identity}`; the aethersdr#2385 crash class is structurally
impossible. What remains for multi-radio (aethersdr#3445) is feature/design work
— the `m_sessions.size() > 1` activation, the active-radio UI, the
audio-plane decision — which is the team's call, not more refactoring.

Refs aethersdr#3351 aethersdr#3445 aethersdr#3384