…2768). Principle I.

Phase A — extract the 119-line inline construction at MainWindow.cpp:6548
into src/gui/TxBandDialog.{cpp,h} as a real class, parameterized on
RadioModel*. The active TX-profile is snapshotted into the window title
at construction (WA_DeleteOnClose means the dialog is reconstructed on
every open, so the title stays current without a profileChanged signal).

Phase B — inherit from PersistentDialog so the geometry persists across
launches under AppSettings key TxBandDialogGeometry, and the frameless
title-bar / FramelessResizer plumbing comes from the base class. The
lazy-construct site in MainWindow becomes a one-liner showOrRaisePersistent
call, and the m_txBandDialog branch in setFramelessWindow() is removed
because the m_persistentDialogs registry handles propagation.

FlexLib semantics preserved verbatim — every transmit bandset / interlock
bandset command (rfpower, tunepower, inhibit, hwalc_enabled, acc_tx_enabled,
rca_txreq_enable, acc_txreq_enable, tx{1,2,3}_enabled) is sent exactly as
the inline code did. Principle I: FlexLib is the protocol authority, and
these are the canonical setter forms in transmit-bandset / interlock-bandset
parsers — do not paraphrase.

Follow-up to #2742 (ProfileImportExportDialog migration) and second of three
under the #2679 umbrella (PropDashboardDialog #2767 first, RadioSetupDialog
to follow).

Blast radius: risk_score=0.363, 5 high-risk affected (top:
AetherSDR::MainWindow::MainWindow, AetherSDR::AppSettings::instance,
AetherSDR::MainWindow::buildMenuBar). All high-risk hits are structural
bridges (MainWindow ctor, buildMenuBar, AppSettings) reached only through
the existing setFramelessWindow + showOrRaisePersistent pattern that PR
#2742 already validated; no new structural edges introduced.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Mechanical migration matching PR #2742's recipe (1/3 of the umbrella
PersistentDialog work tracked in #2679):

- PropDashboardDialog.h now inherits from PersistentDialog; drops the
  manual m_titleBar/m_bodyLayout members and the setFramelessMode decl
  (provided by the base class).
- Constructor delegates to PersistentDialog("HF Propagation Dashboard",
  "PropDashboardDialogGeometry", parent) and installs content into
  bodyWidget() instead of a hand-rolled body widget.
- Drops the standalone setFramelessMode() impl and the inline
  FramelessResizer::install(this) bootstrap.
- MainWindow::showPropDashboard() collapses to a single
  showOrRaisePersistent(m_propDashboardDialog, m_propForecast) call.
- Removed the qobject_cast<PropDashboardDialog*> branch from
  setFramelessWindow(): the m_persistentDialogs registry already
  auto-propagates frameless toggles to every PersistentDialog-derived
  child.
- Retyped m_propDashboardDialog from QPointer<QDialog> to
  QPointer<PropDashboardDialog>.

The user-facing window title is preserved verbatim ("HF Propagation
Dashboard") — Principle III: on-screen labels are inviolable for the
user, so the abbreviation in the recipe was not adopted. closeEvent
recipe step is a no-op for this dialog (no override exists; base class
handles geometry-flush on close).

Geometry persists under AppSettings key PropDashboardDialogGeometry.
No behavior change to refresh logic, charts, panels, or the
NetworkAccessManager fetch path.

Blast radius: risk_score=0.163, 2 high-risk affected (top: MainWindow::MainWindow, MainWindow::buildMenuBar). Both are reached through the usual MainWindow include of PropDashboardDialog.h; all PropDashboardDialog references in src/ are accounted for and updated.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>