task: split Button and buzzer into Node Settings and Message Settings (#975) #978

Parent: #975

Corrected 2026-10-24. The first version said a buzzer-only radio gets "a dead button section or nothing" from today's screen. That was wrong: device_ui_view.dart:41-42 already shows each half from its own bit, and only the entry tile is gated on the OR. It also used the T1000-E as the buzzer-only example; that board has both. The firmware question it waited on is answered, below. This is a placement change, not a gating fix.

Split the Button and buzzer screen into two independently placed panes.

Today one entry tile, "Button and buzzer" (settings_screen.dart:465-489, body DeviceUiView), lives under Node Settings and is shown when either supportsButtonMatrix || supportsNotifyScope. Inside it each half already follows its own bit. The problem is that the buzzer has nothing to do with the node's identity, and a buzzer-only radio shows an entry titled for a button it does not have.

Build

• Button actions stays under Node Settings, shown only when caps byte 2 0x02 (OFFBAND_CAP2_BUTTON_MATRIX) is set.
• Buzzer and tones moves into Message Settings beside Notifications, shown only when caps byte 2 0x01 (OFFBAND_CAP2_NOTIFY_SCOPE) is set. Message Settings already advertises "Notifications and message handling" in its subtitle.
• Both halves keep their current behavior and wire writes; only placement and the entry gates change.

Firmware facts (answered, verified on firmware-base)

The two bits are set independently: NOTIFY_SCOPE where PIN_BUZZER is defined, BUTTON_MATRIX where PIN_USER_BTN is (MyMesh.cpp:3012, :3018). Real buzzer-only boards, confirmed by AmberForge 2026-10-24: m5stack_unit_c6l, thinknode_m9, wio-tracker-l1-eink. Nothing is needed from firmware.

Sequenced after #969 because both edit settings_screen.dart (file-convergence rule).

Done when

• All four combinations render correctly: button only, buzzer only, both, neither. A radio without a capability shows no row for it and emits no command for it.
• flutter analyze and flutter test clean.

Filed by MistyLynx (session 6c0d5797).