…ust/#2780) (#2786)

## Summary

Cherry-pick of @rfoust's panadapter persistence and macOS GPU lifecycle
work from PR #2780, applied cleanly onto current main with the
stale-snapshot reverts left out.

## Why a cherry-pick rather than merge of #2780

PR #2780 was based on commit \`a0512d99\` (PR #2772 merge), and its
single Codex-generated commit included **stale-snapshot content for
files outside the intended scope**. Squash-merging #2780 as-is would
have silently reverted two recently-landed PRs:

- **PR #2770** (\`aether.ax25\` Q_LOGGING_CATEGORY consolidation) —
\`AetherAx25LibmodemShim.cpp\`, \`Ax25HfPacketDecodeDialog.cpp\`, plus
the test-target linkage in \`CMakeLists.txt\`
- **PR #2772** (RadioSetupDialog → PersistentDialog migration) —
\`RadioSetupDialog.{cpp,h}\`

Verified by three-way merge dry run: post-merge state showed \`class
RadioSetupDialog : public QDialog\` (pre-#2772) and 5 occurrences of
\`lcAetherAx25Shim\` (pre-#2770).

The actual panadapter work in PR #2780 is real and valuable, so this PR
extracts it onto a fresh branch from current main and skips the
unintentional reverts.

## What's in this PR (= the intended scope of #2780)

Cherry-picked verbatim from #2780:

| File | Change |
|---|---|
| \`src/gui/MainWindow.{cpp,h}\` | Persist/restore PanadapterLayout +
FloatingPanIds; expand layout count handling from 4 to 8 pans; preserve
unseen floating IDs across reconnect |
| \`src/gui/PanadapterStack.{cpp,h}\` | Sensible-fallback
docked-splitter layouts when some pans are floating or saved layout
count mismatches |
| \`src/gui/SpectrumWidget.{cpp,h}\` | macOS QRhiWidget lifecycle:
\`WindowAboutToChangeInternal\` before reparent; QRhi resource release
during shutdown while parent backing stores are valid; guarded late
callbacks; auto FFT floor relock after geometry/ypixels changes |
| \`src/core/PanadapterStream.cpp\` | Defensive dBm-range clamping (-180
floor, ≥10 dB span); FFT decode clamps pixel input and dbm output to
range |
| \`src/models/RadioModel.cpp\` | Use actual FFT pane height for radio
\`ypixels\` rather than total widget height |

Net: **+548 / -215** across 8 files.

## What was NOT cherry-picked (stale-snapshot reverts)

| File | Reason |
|---|---|
| \`CMakeLists.txt\` | -7 lines reverting #2770's test-target linkage I
added to fix the link error |
| \`src/core/tnc/AetherAx25LibmodemShim.cpp\` | Robbie's content has
local \`Q_LOGGING_CATEGORY(lcAetherAx25Shim, ...)\` — pre-#2770. Main
has the consolidated \`lcAx25\` from LogManager |
| \`src/gui/Ax25HfPacketDecodeDialog.cpp\` | Same pattern —
\`lcAetherAx25Dialog\` local, pre-#2770 |
| \`src/gui/RadioSetupDialog.{cpp,h}\` | Robbie's diff was **100% pure
revert** of #2772 — no new content, no panadapter-related additions.
Confirmed by inspecting the full \`git diff a0512d9..e72d7e4 --
RadioSetupDialog.cpp\` output |

## Attribution

Commit author is set to **Robbie Foust** so his contribution shows in
\`git log\` and the contributor stats. PR #2780 is being reset to
**Draft** (not closed) so Robbie has a clean reference point + can
update with fresh work if he wants.

## Test plan

- [x] Local build clean (402/402 link, only pre-existing warnings)
- [x] Three-way merge dry-run against current main: clean
- [ ] Manual on Linux: multi-pan layout, detached panadapter, restart,
confirm layout + detached state restore
- [ ] Manual on macOS GPU build: two detached panadapter windows, Cmd-Q,
restart, confirm both restore without the QRhi cleanup callback crash
- [ ] Manual: detach/redock panadapter and confirm auto FFT floor
relocks

## Cross-references

- Replaces #2780 (will be set to Draft after this PR opens)
- Same stale-snapshot pattern as aetherclaude #34 (Claude Code), but
from OpenAI Codex this time — worth a heads-up to whoever's watching
agent-output quality

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Robbie Foust <rfoust@duke.edu>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

…ersistent (#2781). Principle III.

Settings → FlexControl, Settings → USB Cables, and the XVTR overlay button each
called `new RadioSetupDialog(...)` directly, bypassing the m_persistentDialogs
registry that PR #2772 (RadioSetupDialog → PersistentDialog migration) set up.
Symptoms: clicking any two entries opens two windows, frameless toggle skips
the shortcut-opened dialog, and "first opener wins" signal wiring diverges.

This pass routes all four entry points (primary Radio Setup, FlexControl, USB
Cables, XVTR overlay) through showOrRaisePersistent + selectTab, and factors
the txBandSettingsRequested / serialSettingsChanged / sliceLetterDisplayModeChanged
/ QDialog::finished wiring into a single private helper wireRadioSetupDialogSignals
so a fresh construction picks up the full handler set regardless of which menu
clicked first.  The dialog now lives in m_persistentDialogs unconditionally, so
the special-case qobject_cast in setFramelessWindow is removed — the
persistentDialogs loop below already handles it.

Also re-asserts the primary Radio Setup entry's #2772 migration that #2786
silently reverted during a panadapter-layout merge.

Blast radius (codegraph impact on MainWindow::buildMenuBar, max_depth=3):
risk_score=0.7297, 18 high_risk affected (top: MainWindow::MainWindow,
AppSettings::instance, AppSettings::value).  The score reflects buildMenuBar's
breadth across the menu surface; the actual edit is four lambda bodies plus a
helper, none of which alter buildMenuBar's caller-facing contract.  No new
test-target link dependencies (wireRadioSetupDialogSignals is private to
MainWindow.cpp, RadioSetupDialog.h was already #included).