…keyboard nav (#3303)

Companion to #3288 (Phase 2 accessibility audit), per maintainer
guidance from @jensenpat.

Addresses all four issues from the @jensenpat review on the previous
iteration.

## What's in this PR

### Phase 2a — `setAccessibleName` on previously unnamed widgets

All changes are additive, no behavioral risk.

**MeterApplet** (`MeterApplet.cpp`): PA temperature, supply voltage,
main fan speed gauges

**AmpApplet** (`AmpApplet.cpp`): Forward power, SWR, drain current
gauges — rebased onto the new row-label/ballistics layout from #3301

**TunerApplet** (`TunerApplet.cpp`): Forward power, SWR gauges + C1/L/C2
relay bars — rebased onto the same row-label refactor

**SpectrumWidget** (`SpectrumWidget.cpp`): "Panadapter spectrum display"

**TciApplet / DaxApplet**: RX 1–N gain sliders, TX gain slider (named in
loop)

### Phase 2b — Live accessibility announcements

**VFO frequency** (`VfoWidget.cpp` / `VfoWidget.h`):
- `updateFreqLabel()` now routes through
`scheduleFrequencyAnnouncement()` — a 300 ms single-shot debounce timer
that fires once the frequency settles, preventing VoiceOver from being
asked to speak ~20 times/second during active wheel tuning
- LOCKED state announces immediately (user-triggered, infrequent) but
suppresses repeats while the 500 ms lock-feedback gate is active

**S-meter** (`SMeterWidget.cpp`):
- `setFocusPolicy(Qt::TabFocus)` added — widget is keyboard-reachable
- `setLevel()` announces the *displayed* value, not raw dBm: in S-Meter
Peak mode the event value is derived from `m_peakDbm` (what the needle
and text readout show), not `m_levelDbm`; formatted as "S7, -79 dBm" to
match the painted readout exactly

**MeterSlider** (`MeterSlider.h`):
- `setFocusPolicy(Qt::TabFocus)` added — DAX/TCI gain sliders are now
keyboard-reachable
- `keyPressEvent` handler: Left/Down −5%, Right/Up +5% — gain thumb is
adjustable without a mouse

### Phase 2c — VFO tab bar: `QLabel` → `QPushButton`

VFO tab labels were `QLabel` with a click event filter; VoiceOver could
not activate them. Replaced with `QPushButton` throughout
(`VfoWidget.cpp`, `VfoWidget.h`).

### Phase 2d — Keyboard navigation: RelayBar + PhaseKnob

- `RelayBar` gains arrow-key support (Left/Right step through relay
positions)
- `PhaseKnob` excluded from the tab order (it is already accessible via
the paired ESC sliders)

## Test notes

On macOS with VoiceOver:
1. Tab to the S-meter — subsequent signal level changes should be spoken
as "S7, -79 dBm" etc.
2. Tune the VFO wheel quickly — VoiceOver speaks once after tuning
settles (not on every step)
3. Lock the VFO — VoiceOver speaks "LOCKED" once
4. Tab to a DAX/TCI gain slider — Left/Right arrows move the thumb
5. VFO tab bar buttons ("DSP", "USB", "X/RIT", "DAX") are activatable
via VoiceOver

— AI5OS (@w9fyi)

…hersdr#3301)

Limit the RADE activation filter to the FreeDV waveform passband: 750-2250 Hz for DIGU and -2250 to -750 Hz for DIGL.

This change is localized to MainWindow::activateRADE and does not alter the regular DIGU/DIGL filter handling used by modes such as FT8.

…keyboard nav (aethersdr#3303)

Companion to aethersdr#3288 (Phase 2 accessibility audit), per maintainer
guidance from @jensenpat.

Addresses all four issues from the @jensenpat review on the previous
iteration.

## What's in this PR

### Phase 2a — `setAccessibleName` on previously unnamed widgets

All changes are additive, no behavioral risk.

**MeterApplet** (`MeterApplet.cpp`): PA temperature, supply voltage,
main fan speed gauges

**AmpApplet** (`AmpApplet.cpp`): Forward power, SWR, drain current
gauges — rebased onto the new row-label/ballistics layout from aethersdr#3301

**TunerApplet** (`TunerApplet.cpp`): Forward power, SWR gauges + C1/L/C2
relay bars — rebased onto the same row-label refactor

**SpectrumWidget** (`SpectrumWidget.cpp`): "Panadapter spectrum display"

**TciApplet / DaxApplet**: RX 1–N gain sliders, TX gain slider (named in
loop)

### Phase 2b — Live accessibility announcements

**VFO frequency** (`VfoWidget.cpp` / `VfoWidget.h`):
- `updateFreqLabel()` now routes through
`scheduleFrequencyAnnouncement()` — a 300 ms single-shot debounce timer
that fires once the frequency settles, preventing VoiceOver from being
asked to speak ~20 times/second during active wheel tuning
- LOCKED state announces immediately (user-triggered, infrequent) but
suppresses repeats while the 500 ms lock-feedback gate is active

**S-meter** (`SMeterWidget.cpp`):
- `setFocusPolicy(Qt::TabFocus)` added — widget is keyboard-reachable
- `setLevel()` announces the *displayed* value, not raw dBm: in S-Meter
Peak mode the event value is derived from `m_peakDbm` (what the needle
and text readout show), not `m_levelDbm`; formatted as "S7, -79 dBm" to
match the painted readout exactly

**MeterSlider** (`MeterSlider.h`):
- `setFocusPolicy(Qt::TabFocus)` added — DAX/TCI gain sliders are now
keyboard-reachable
- `keyPressEvent` handler: Left/Down −5%, Right/Up +5% — gain thumb is
adjustable without a mouse

### Phase 2c — VFO tab bar: `QLabel` → `QPushButton`

VFO tab labels were `QLabel` with a click event filter; VoiceOver could
not activate them. Replaced with `QPushButton` throughout
(`VfoWidget.cpp`, `VfoWidget.h`).

### Phase 2d — Keyboard navigation: RelayBar + PhaseKnob

- `RelayBar` gains arrow-key support (Left/Right step through relay
positions)
- `PhaseKnob` excluded from the tab order (it is already accessible via
the paired ESC sliders)

## Test notes

On macOS with VoiceOver:
1. Tab to the S-meter — subsequent signal level changes should be spoken
as "S7, -79 dBm" etc.
2. Tune the VFO wheel quickly — VoiceOver speaks once after tuning
settles (not on every step)
3. Lock the VFO — VoiceOver speaks "LOCKED" once
4. Tab to a DAX/TCI gain slider — Left/Right arrows move the thumb
5. VFO tab bar buttons ("DSP", "USB", "X/RIT", "DAX") are activatable
via VoiceOver

— AI5OS (@w9fyi)